Chairman STOKES. The committee calls Dr. Barger. Doctor would you stand and be sworn? Do you solemnly swear the testimony you will give before this committee is the truth, the whole truth, and nothing but the truth, so help you God?
TESTIMONY OF JAMES E. BARGER
Dr. BARGER. I do
Chairman STOKES. Thank you. You may be seated. Mr. Cornwell.
Mr. CORNWELL. Thank you, Mr. Chairman. Dr. Barger, I would like to first direct your attention to the point in time that our chief counsel just made reference to, namely, which the committee brought to you a tape recording of transmissions on on November 22. At that point in time, what did the committee ask you to try to do with that tape recording?
Dr. BARGER - Mr. Cornwell, there was a series of questions that were asked in increasing order of difficulty. The first question and the least difficult potentially to answer was, simply, was the motorcycle with the stuck transmitter likely to have been in Dealey Plaza. If so, was the sound of shots recorded thereon or detectable thereon. And if that turned out to be the case, how many shots. If that could be determined, what was the time sequence between them, and if that could be determined, from what locations were the shots fired. And if by chance that also could be determined, what weapons fired the shots?
Mr. CORNWELL - Would there be some reason to believe that you could answer any or all of these questions?
Dr. BARGER - Well, the reason to believe that there may be answers to the latter questions was, of course, less likely than the former ones, but the answer was generally yes. The tapes had a good deal of noise on them, motorcycle noise, crowd noise, radio frequency interference, and the like. The most serious problem was the motorcycle noise. There is a way to help reduce that. It is a technique called adaptive filtering. It considers that the motorcycle is a repetitive device. As the cylinders fire, they do so periodically. The adaptive filter can learn to understand the event and project what will happen the next time the piston fires and subtract that noise out from the tape. We thought once the adaptive filtering was conducted, the tape might then be noise-free enough to attempt a detection of the sounds of gunfire. Now it was perfectly clear that these sounds were not clearly audible. There is in the field of detection theory a favorite approach called matched filtering. The matched filter is a device that is used to detect events that you have some understanding of even though they are subaudible. Matched filters are used in radar sets commonly to detect the presence of impulsive signals in noise, even though they are not visible or audible in the raw data. There was reason to believe that applying these techniques we might be able to detect the impulsive sounds of gunfire.
Mr. CORNWELL - What, if anything, gave you reason to believe that you might be able to determine the direction from which gunfire came or the fact that it was gunfire?
Dr. BARGER - When an impulsive source of sound is generated in an enclosed or semi-enclosed environment, such as an urban environment, the implusive sound spreads from the place where the sound was generated in all directions and is reflected, scattered, and diffracted into all possible receivers, such as microphones that might be stuck and such as cars. Now the impulsive signals that arrive at these receivers--microphones or ears--over all of these paths through the processes of reflection, and scattering, occur in a unique pattern, and that pattern depends on where the source of sound was and where the receivers at that time. This unique pattern can be learned by, for example, reconstructing the sound of the acoustical event and measuring the unique pattern. If the microphone or receiver moves from one place to another, the pattern will change, and it is in fact these echo patterns that are the matching patterns that we considered using in the matched filter as a very powerful method for detecting the possible presence of gunfire in the tapes.
Mr. CORNWELL - Let's begin with what you described as the unique sound of gunfire, and at this point show you JFK exhibit F-357. First, will you simply tell us what that is?
Dr. BARGER - This is an exhibit that illustrates the acoustical disturbance generated by a rifle firing a supersonic bullet in free space.
Mr. CORNWELL - At this time, Mr. Chairman, I would ask that that exhibit be admitted into evidence so that we may ask Dr. Barger further questions concerning it.
Chairman STOKES - I am sorry, Counsel? I didn't hear you.
Mr. CORNWELL - I would like to ask at this point if that exhibit might be admitted into evidence.
Chairman STOKES - Without objection, it may be entered. [The information follows]
JFK EXHIBIT F-357
Mr. CORNWELL - Would you at this point then, Dr. Barger describe this phenomenon using the exhibit?
Dr. BARGER - This simple diagram shows the location of a rifle firing a supersonic bullet along this horizontal trajectory. At the instant in time that this illustration depicts, the bullet is at position 1. The sound generated by the muzzle blast is expanding spherically around the origin of the gunfire, namely, the muzzle of the rifle. At the time depicted here, that impulsive sound spherical surface has reached the point shown by the circle. The bullet, however. being faster than the speed of sound has advanced beyond the position of the sound wave. It generates a shock wave as a supersonic transport would and the locus of that shock wave is from the bullet itself to the tangent of the sound wave at this point At a later time [now referring to the second exhibit] the bullet will have advanced, and both the shock wave and the sound wave would have expanded to the position shown here. The sound wave has expanded to this point, and the shock wave has progressed to this region. If an observer were at this point, at the first time that I showed, when the bullet was at this point, the observer would hear the shockwave because it would pass him at that time. At the second time that I show here, when the bullet is advanced to the second position, the sound waves of the rifle would reach the observer at that point and he would then hear the muzzle blast.
Mr. CORNWELL -You have emphasized at several points that this is a diagram showing the principles with respect to a supersonic bullet. What, if any, differences would you find if the bullet were subsonic?
Dr. BARGER - If the bullet were subsonic, at the first time that I have shown when the muzzle blast has reached this point, the bullet would have lagged behind the position of the sound wave at that point, and it would always be behind; getting farther and farther behind, as time went on; and no shockwave is generated by that bullet.
Mr. CORNWELL If you wanted to look at those principles on a recording, would there be a way that you could do that?
Dr. BARGER - Yes. This observer is the same as the receiver I spoke of earlier. It could be a microphone or a near, and there fore what I said for this observer holds for the----
Mr. CORNWELL - I would like at this point then to show you JFK exhibit F-364 and ask you if you could tell us what that is.
Dr. BARGER - This is an illustration of the shape of the acoustical wave form generated by two rifles.
Mr. CORNWELL - At this point, Mr. Chairman, I would like to ask that JFK exhibit F-364 be admitted into evidence.
Chairman STOKES - Without objection, it may be entered into the record at this point. [The information follows:]
JFK EXHIBIT F-364
Mr. CORNWELL Would you now, Dr. Barger, tell us what that exhibit illustrates?
Dr. BARGER - At the top of the illustration we show the acoustical waveforms of both the shock wave and the muzzle blast from a Mannlicher-Carcano. The shock wave was measured by a microphone 10 feet from the trajectory of the bullet and the muzzle blast was measured by the same microphone which was at the same time 30 feet from the muzzle. All of the acoustical pressures are plotted here as a function of time measured in milliseconds. The shock wave is a very sharp event looking something like the letter "N," capital letter"N"and in this case, with this weapon, the peak pressure of the shockwave is 130 decibels. Now let me just briefly describe the decibel as a measure of acoustical intensity. The reference pressure for the decibels that I describe is 2 times 10 to the minus 5 newtons per square meter the currently standard reference pressure. With respect to that pressure, the shockwave has an intensity of 130 decibels. The muzzleblast at 30 feet is more intense. It has an intensity of 137 decibels. Let me just give you a few facts about decibels that will help make this clear. If two sounds are otherwise similar but have a different loudness, a different intensity by 10 decibels, the louder of the two will sound twice as loud. On the other end of the scale, if two sounds are so slightly different in intensity that you can just perceive that difference, they will be different by 3 decibels. The muzzle blast then, more intense by 7 decibels, would sound almost twice as loud as the shockwave. It has a very sharp peak, a negative undershoot followed by quiescence, and these are characteristic of the waveforms of that rifle. A rifle firing a bigger charge is the M-l rifle. It also has a faster round. The muzzle velocity of the Mannlicher-Carcano is about 2,000 feet per second. The M-I is close to 3,000. Therefore the intensity of the shock wave radiated by the M-I is greater--being about 140 decibels when measured 10 feet from the flight path--is twice as loud as the Mannlicher-Carcano shockwave. The muzzle blast is also more intense. At 30 feet it would be about 145 decibels, being something less than twice as loud as the Mannlicher-Carcano.
Mr. CORNWELL - I suppose we are all aware that the Dallas Police Department found a Mannlicher-Carcano on the sixth floor of the book depository, and the Warren Commission concluded that was the weapon used in the assassination. So I guess from that we could assume why you chose a Mannlicher-Carcano in the top graph to illustrate the principles you just described. But why did you choose an M-1 to illustrate in the lower portion of the graph?
Dr. BARGER - Well, for one reason we had the data. The principal reason was that it is the loudest rifle that one could conceive might have been used in that environment. And the purpose then is to show that the loudest one we might have conceivably used is less than twice as loud.
Mr. CORNWELL - I would like to now direct your attention to the part of your previous resume that referred to the fact that you might be able to locate the shots and ask you if you would direct your attention at this time to JFK Exhibit F-334. Dr. BARGE..Yes. This is what is known in the field of scientific presentation as a cartoon. It illustrates the formation of echo patterns in urban environments.
Mr. CORNWELL - At this time, Mr. Chairman, I would ask that JFK exhibit F-334 be admitted into evidence.
Chairman STOKES. Without objection, it may be entered in the record at this point. [The information follows:]
JFK EXHIBIT F-334
Mr. CORNWELL - Would you explain then what the principles are that are illustrated by that?
Dr. BARGER - Yes. I have said we are aiming for the application of a matched filter to the Dallas Police tape that Mr. Blakey described, seeking the possible detection of gunfire there upon. Now the pattern that will be the match in this filter would be an echo pattern as generated at a receiver, such as a microphone, in an urban environment that has buildings and an impulsive sound source that might have been generated in one of them. In the lower figure here, we show, along the horizontal scale, time increasing, and in the vertical scale here the amplitude of sound that might arise at any particular time. Now the sound from the muzzle of the rifle expands as I showed in the first exhibit, and it propagates along this direct path, which is the path having the least length between the source and the microphone. But I have illustrated that there are two here very close together marked D1 and D`2. The reason for that is that next to the direct path is another ray of sound that hits the street just below the microphone and reflects up into the microphone. Those two paths have very nearly the same length, therefore, they occur at very nearly the same time, and they have very nearly the same amplitude, and so I have plotted them at this same point. Now, sound propagating over this direct path loses energy only by spreading out to fill the sphere that I described in the first exhibit. Sound paths having the next highest amplitude are those that are reflected from the surface of a building. Reflection occurs when ever the angle of the sound ray incident upon the building is reflected from it at the same angle. The same sound that hit the building was reflected off. It is still going after reflection in only one direction, just as it was before reflection. Therefore, it has not been diminished in intensity. It has merely had the direction of its propagation changed. It then hits the microphone as does another similar path hit the street and then the microphone. These two paths being longer occur later. They are marked with R1 and R2 here, illustrating the reflected direct and reflected surface bounce path. The sounds that comprise echo patterns that have the next stronger amplitudes are the diffracted paths. These paths hit large edges such as the corner of a building. Now when the sound strikes the corner of that building, it is spread out in a plane that I am now describing with this pointer. It goes into all directions within that plane, including the direction of the microphone. Since some of the sound that hit that corner at that time went in other directions it is diminished in amplitude at the time it arrives at the microphone. Therefore, Path M that I just described, which is clearly shorter than the Path R because this corner is closer to the source than was the reflection path is right there, has a lower amplitude than the reflective path had. The furtherest corner of the building will give a diffracted path similarly. Now, we have discussed reflections and diffractions. The third most important, but generally the weakest method of changing the direction of sound is by scattering. I have illustrated a parallelogram here which represents people or automobiles or anything of small size. When the sound hits an object of small size, it is sent out in all directions, including the direction of the microphone. Having been sent in all directions in space, it is diminished in amplitude considerably, so only if that scattering occurs close to the microphone, as I have shown here, or if the scattering object, namely this window sill, is close to the source, as I have shown here, will those paths have sensible amplitude. In order to have significant amplitude, the scattering object has to lie close to the direct path. Therefore the travel time over the scatter path has to be only slightly larger than the travel time over the direct path. Therefore, right after the loud sound arrival you see lots of weaker sound arrivals that are scattered from small objects. There are other buildings, of course, in a typical urban environment and in particular, in Dealey Plaza, and so there are diffracted and reflected sound paths coming in, as I have illustrated with a simple "U" here from other directions. They will occur at later times because they come from buildings that are further away and they will be scattered out in time. A cursory examination shows we would expect echo patterns that would persist for about 1 second. In that period of time there would be on the order of 10 or 12 reflected, diffracted and scattered paths having significant amplitude, namely, amplitudes above some threshold below which exists only noise.
Mr. CORNWELL - If I understand correctly then, the sound would travel at the same rate of speed after it hit any of those surfaces no matter whether it was reflected or scattered or whatever, and therefore the spacing of the marks on a time scale would be detemined strictly by the distances that the sound had to travel from its source to the microphone or ear, is that correct?
Dr. BARGER - That is correct.
Mr. CORNWELL - In your hypothetical urban environment that you show there on JFK exhibit F-334, how many different points of sound source, or different locations for a point of sound source, and how many different locations for a microphone, might you expect to produce the exact same spacing of the points on the time scale and amplitude at those points?
Dr. BARGER - It is clear that moving the portion of this microphone in any direction will alter the relative length of the sound paths and therefore alter the spacing between them. If there are enough different reflectors and scatterers, then the pattern achieved at any particular point is unique and would not be replicated at any other point.
Mr. CORNWELL - If we had a time scale such as shown at the bottom, you would expect that to be produced from a sound only in one place in the enviroment and at a point where the microphone or receiving ear was located at only one point?
Dr. BARGER - That is correct. In the absence of noise, if you could measure this pattern precisely it would uniquely fix the position of the microphone.
Mr. CORNWELL - Now, you told use earlier that when you received the tape recording here in question you listened to it and had a large amount of noise or static in it, is that correct?
Dr. BARGER - That is correct.
Mr. CORNWELL - What did you do after initially listening to this recording?
Dr. BARGER - Initially we listened to the whole tape and we found a tone point on the tape a 5 1/2-minute segment in which the sound of a motorcycle engine and other noises were heard continuously. This particular 5 1/2-minute segment was the period of the stuck microphone button that Professor Blakey described earlier. The sound in that 5 1/2-minutes was mostly motorcycle noise. However, there was a period halfway through it, approximately, where the motorcycle noise diminished. That is a brief description of what we heard. Now, as I said, we realized from the out set that we were seeking to detect sub-audible events or at least not audibly recognizable events and this is helped by looking at the electrical waveform that represents the sounds in a form called a waveform chart. So the first thing we did was to digitize the sounds in this 5 1/2-minute tape recording to form a computer file of the information contained by that digitalization, and then plot out a chart showing the waveform on the tape. This process was conducted by Dr. Wolf at BBN and it generated about 234 linear feet of waveform.
Mr. CORNWELL - I now show you JFK exhibit F-335 and ask you if you can tell us what that is?
Dr. BARGER - That is about ten feet of the 234 feet of waveform.
Mr. CORNWELL - I would like at this time, Mr. Chairman, to ask that that exhibit be admitted into evidence.
Chairman STOKES - Without objection, it maybe entered into the record.
JFK EXHIBIT F-335
Mr. CORNWELL What, if anything, did you learn from the production of this type of chart and your analysis of it?
Dr. BARGER - This exhibit shows the waveform of the sounds on the tape displayed at 50 inches per second starting 130 seconds after the onset of the stuck microphone button and extending to the time of 141.6 seconds. Of course, it is difficult to see here without at telephoto lens but I will describe it to you. This continuation of rather constant level noise is typical of what preceded this segment for about 2 minutes. It is motorcycle noise. At this time, about 132 seconds after the microphone button became stuck, it is clear that the amplitude of that noise is diminishing. Shortly after that time, a series of impulsive events are seen in the tape. We concluded that it is possible that some of these impulsive events are in fact what an echo pattern would look like as transmitted through the radio in question.
Mr. CORNWELL - In addition to the motorcycle noise, did you find on your graph other types of noise or static, something like that?
Dr. BARGER - Yes. I just mentioned briefly that in addition to this continuum of noise which sounds like and apparently is motorcycle noise, there are sharp impulsive events of this type. They occur from time to time. Many of these have become understood by us to be impulsive events caused by other radios when they key in and attempt to transmit on this radio channel as well.
Mr. CORNWELL - After 15 years in what condition was the tape? Did that possibly have any effect on the level of noise that you found?
Dr. BARGER - The possibility that some of this noise was caused by the tape recording process is clearly are alone. The noises generated by the motorcycle are so intense that the noises generated by the recording process are relatively less. Therefore that is not the principal source of disturbance.
Mr. CORNWELL - After reviewing the output in this form, what did you do next?
Dr. BARGER - We realized that we could see impulsive events occurring at times after the motorcycle noise diminished of its own accord. We have then to determine whether such impulsive events might also be present in the tape recording at earlier times before the motorcycle in fact quieted down. We decided the best way to do that, as I mentioned briefly before, was to filter this tape recording through an adaptive filter that would, as I described it, learn about the motorcycle noise, project slightly ahead, and subtract it out.
Mr. CORNWELL - There might be members of the committee who are familiar with some types of filters, but the particular type that you needed for this process, was it available in 1963?
Dr. BARGER - No.
Mr. CORNWELL - When, approximately, would it have been developed, do you know?
Dr. BARGER - I am not exactly sure. The type of adaptive filter we used is called a Widrow adaptive filter. We used the least means squares logarithm to compute the filter weights. I don't believe that process was described in the literature until 1968 or so.
Mr. CORNWELL - I would like to show you JFK exhibits F-336A and F-336B. Would you tell us what those are, please?
. BARGER. These are about 18 feet of the waveforms that were obtained by filtering the motorcycle tape through the adaptive filter. The beginning time of this segment is 130 seconds after the onset of the stuck button, as was the previous exhibit. In this case, the terminating time is 150 seconds.
Mr. CORNWELL - I would ask at this point, Mr. Chairman, that JFK exhibits F-336A and B be admitted into evidence.
Chairman STOKES. Without objection, they may be entered into the record at this point. [The information follows:]
JFK EXHIBIT F-336A & B
Mr. CORNWELL Did you learn anything new from reviewing the data in this filtered form?
Dr. BARGER - Yes, we did, but these waveforms are sufficiently indistinct to you that you wouldn't be able to tell it from where you are sitting. The amplitude of the noise in the portions of the record where the motorcycle was heard most loudly have been reduced relative to the amplitude of the signals in the period where the motorcycle noise had previously and is still quiet. It, therefore, enabled us to examine those portions of the tape that were recorded when the motorcycle was running faster and during which time the noise of the motorcycle was perhaps obscuring any impulsive sounds that might in fact appear to be echo patterns.
Mr. CORNWELL - What, if any, technique did you apply to learn more about the data after receiving it in this filtered form?
Dr. BARGER - After examining the 234 feet of filtered waveforms we discovered there were no other impulsive events on the tape that had been masked by the motorcycle noise, with one exception. That impulsive series of events came near the end of the 5-minute segment and was very unlike the series of impulsive events that we see before us here, at times around 130 seconds after the stuck button.
Mr. CORNWELL - What, specifically, did you do to determine what the nature of the impulsive events were?
Dr. BARGER - At this stage we conducted a series of tests which we call screening tests, to determine whether those impulsive events might be ruled out as gunfire. I might add before we did that we did attempt some different analyses beyond those that I have described so far, that would help us understand the nature of the impulsive events that we did in fact perceive. The first of those analyses, in fact, was a calculation of the spectrographic analysis of some of the transient events.
Mr. CORNWELL - I would like to show you JFK exhibit F-356 and ask you, Would it be possible for you to use that exhibit to illustrate the analysis, the spectrographic analysis you just mentioned?
Dr. BARGER - Yes. This exhibit is made up of two spectrographs of two segments of the tape recording that help explain the presence of some of the impulses on the tape.
Mr. CORNWELL - May we have JFK exhibit F-356 admitted into evidence Mr. Chairman?
Chairman STOKES - Without objection it may be entered at this point. [The information follows:]
JFK EXHIBIT F-356
Dr. BARGER - There were a series of impulsive events on the tape that were particularly numerous at times about 145 seconds to 150 seconds. These are shown in a spectrogram as follow: The time on the spectrogram is marked on the horizontal scale in seconds. The frequency of the energy in the sounds on the tape at each time is marked on the vertical scale in kilohertz. At this point, half a kilohertz, is the frequency approximately equal to the pitch of middle C on a piano. The height of these spikes -- the distance the spike reaches upward in this coordinate indicates how sharp it is, how much high frequency content it contains, but that is about all. The interesting thing shown are these horizontal dark bands. The horizontal dark bands are the sounds made visible in the spectrogram that are caused by the heterodyning between two radio transmitters. The radio transmitter with the stuck microphone is transmitting for sure. There are other radios that transmit on the channel, which puts their carrier frequency onto the air as well. The carrier frequencies of the two radios are not exactly the same. They beat between each other and generate what is called a heterodyne tone, a beep. The indication of that beep, which would be determined by where it was positioned in the vertical dimension of the spectrogram, is dependent on the exact radio in question and what its carrier frequency really is. We see there are heterodyne tones with this pitch, this pitch and this pitch, and even with this pitch. That indicates that during this time there were at least four other radios that were briefly trying to transmit by pressing their talk buttons. When they realized the channel was still in use, they let it up. So the time between when they push the button, which generates a transient, until the time they let up the button, which also generates a transient, there is a heterodyne tone observable in the spectrogram. These tones were subaudible on the tape so the spectrogram revealed their presence. Whenever there were a pair of impulses with a heterodyne tone between them, we knew those impulses were generated by another transmitter and should be eliminated from consideration as possible members of an echo pattern.
Mr. CORNWELL - In addition to the spectrographic analysis you have just described were there any other techniques that you utilized in order to determine whether or not the impulseses on the tape were infact associated or might be associated with gunfire.
Dr. BARGER - Yes, there was one in particular. We wanted to demonstrate there were audible acoustical sounds on the tape. The sound of a bell toll at 152 seconds from the time of the stuck button was vaguely evident. We wished to analyze that segment of the tape with an energy spectrurn.
Mr. CORNWELL - I show you JFK exhibit F-355 and ask you to tell us what that is.
Dr. BARGER - This is what I just described. The energy spectrum of the segment of the tape that contains the toll of the bell.
Mr. CORNWELL - May we have JFK exhibit F-355 admitted into evidence, Mr. Chairman?
Chairman STOKES - Without objection, it may be entered in to the record at this point. [The information follows:]
JFK EXHIBIT F-355
Dr. BARGER - In this exhibit the frequency of each component of sound is plotted on the horizontal scale and the loudness of that component is plotted on the vertical scale, again in decibels. The nature of an energy spectrum, if you have nothing in the record except noise, is a rather jiggly line, sometimes described as a hairy line, that is rather gently undulating in the frequency domain. However, if there are periodic components in the sound, such as generated by a bell or an overtone of a bell, they will generate a spike in the spectrum such as these spikes that are clearly visible in this exhibit. Infact, there is a harmonic series of periodic events that are visible in this record and we have labeled them with the number 1 to represent the fundamental, and the numbers 2, 3, 4, 5, 6, to represent the harmonic overtones. This particular spectrum, which was calculated by Mr. Schmidt, has been done over a third of a second of the tape that was identified by the audible, but barely audible, sound of this bell. Now, there is a very interesting feature in this spectrum and that is in particular this particular peak. The reason this is of significance is as follows: It is characteristic of the design and manufacture of carillon bells that they contain a harmonic series such as I have numbered here. The fundamental frequency is in the description of carillon sounds called the hum note. The second harmonic is called the strike note and that is the note to which the bell is tuned. In this case that is 440 hertz which is A below middle C. The strike note characteristically has a minor third above it and this peak in the spectrum is at the right frequency ratio to the strike tone to be the minor third of a carillon bell. They typically have a fifth and an upper third above them and both of those overtones are clearly evident in the spectrum of this bell. It is not at all unlikely that a strong seventh overtone of the hum note would appear. This, therefore, is a very clear indication that the bell is a large carillon bell. The sound of it would reach this tape recording only through an acoustical path.
Mr. CORNWELL - So somewhat similar to the spectro graphic analysis technique, by applying the energy spectrum analysis you were again able to identify transients or short peaks in the data which were not associated with gunfire?
Dr. BARGER - That is correct.
Mr. CORNWELL - At this point then you had filtered the tape and you had eliminated both back ground noise, such as the motorcycle, and a number of other transients using the techniques you just described, what conclusions were you able to draw at this point from your analysis?
Dr. BARGER - We concluded there were sounds of acoustical origin on the tape, giving us confidence that the acoustical part of the otherwise partially malfunctioning transmitter was working. We found that there are impulses on the tape that are unique to the segment following 130 seconds from the onset of the stuck button and a cursory examination of those impulses indicated that we could not rule out the possibility that they were in fact echo patterns.
Mr. CORNWELL - What did you do next?
Dr. BARGER - Well, it seemed prudent to do something more than a cursory examination of the echo patterns so we devised six screening tests to determine if they might in fact be the sounds of gunfire. If the echo patterns passed these six screening tests we would proceed to the filter detector which I described before as the most powerful test we could perform. The first screening test was: Did the impulsive patterns on the tape occur at the time of the assassination? The second screening test was, simply: Were these patterns that occurred at this time in the data unique throughout the 5.5-minute segment? In other words, could they be shown to have occurred only once? Third, we asked, did the span of time occupied by the impulse patterns cover at least 5 seconds? Because if they had not, they could not possibly represent the entire span of the gunfire as given by analysis of the Zapruder film. Fourth, we asked, do the shape of the impulses on this tape recording resemble the shape of impulses of gunfire transmitted through that type of radio? They certainly didn't resemble the wave forms of gunfire I showed in the first exhibit, as the radio would be expected to distort them. Would it have distorted them in the way that they appear on the tape? The fifth screening test was: Does the narrow range of observed amplitudes of the impulses on the tape correspond to the expected range of amplitudes for the wide range of echo amplitudes as compressed up on transmission through the radio? The sixth one was: Do the number of impulses that we would expect in an echo pattern in Dealey Plaza approximate the number of impulses that are seen in the tape to occur at this time? Those six questions were asked and they received an affirmative answer.
Mr. CORNWELL - Let me ask you--I believe your explanation perhaps was clear that you wanted to find out if they occurred at the right time of day; if they were unique, in other words, if they were not so thoroughly scattered throughout the data that they were the cause of something else; that their shape was appropriate; that they had the right amplitude or height after the compression of the radio; and that there was approximately the right number of impulses. But you also stated--I believe your third item was that the time span had to be at least 5 seconds. Do I understand--you made reference to the Zapruder film--is that simply a matter of looking at the headshot at 313, or 312, and going back into the film at which point I suppose everyone would agree that the participants, the President and Governor Connally, are clearly reacting, and saying that there was at least a minimum period of time of 5 seconds that the shots had to cover. Is that accurate?
Dr. BARGER - That is accurate.
Mr. CORNWELL - So no matter what else might ultimately be found out about the number of shots, or the timing, or sequencing, or anything else, you at that point were looking to see if at least covered a 5-second span?
Dr. BARGER - That is correct.
Mr. CORNWELL - Then, let's go to the first test and show you JFK exhibit F-366 and ask you if you can tell us what that is?
Dr. BARGER - Yes. This is an illustration of how we attempted to achieve our best estimate of the time of the assassination.
Mr. CORNWELL May we have JFK exhibit F-366 admitted into evidence, Mr. Chairman?
Chairman STOKES. Without objection, it may be entered at this point. [The information follows:]
JFK EXHIBIT F-366
Dr. BARGER - The data depicted in this exhibit were obtained by listening to channel 2 of the Dallas Police Dispatcher System. Channel 2 was in use on that day and at that time by, among others, the chief of police who was in the lead car just ahead of the President. Channel 2, like channel 1, was recorded; the sounds that were carried over channel 2, like 1, were recorded. They were recorded on a Gray Audograph which unfortunately records intermittently. When a radio is broadcasting a signal, the recorder turns on and records the sounds. When no one is recording, the recorder stops. This saves recording space. As a result of that feature, we, in the laboratory, while listening to that tape recording, with a stopwatch, timed the annotations that the dispatcher read out from reading his clock. These times are plotted on the horizontal scale, each time he gave an annotation. For example, if he said 12:28 and our stopwatch read 5.5 minutes we would put a dot there. If he then said 12:28 a half minute later, which was not uncommon-in other words, he would only annotate the tape to the nearest whole minute--we would then note the time that that was heard and plot that point. Now we have then obtained the stopwatch time, or we might say the laboratory time, plotted against the clock time that the Dallas police dispatcher on channel 2 had at that time, and the data follows this bent line. When one has data of this sort one draws a straight line through them by a mathematical procedure called the least squares fit. This straight line that you have drawn becomes your best estimate of the time correspondence between your watch in the laboratory and between the channel 2 dispatchers clock at the Dallas Police Department. At times prior to 12:30 the best estimate by the least squares procedure of the correspondence between laboratory time and Dallas police channel 2 time is a line that has a slope less than one. This indicates that on the average the recorder used to record the dispatchers voice was running very slowly. The reason that perception is given is that it was actually off part of the time when no one was speaking. However, at about 12:30 the voice traffic increased so much on channel 2 that the recorder operated then continuously and thereafter our estimated correspondence between laboratory time as measured on the stop watch and Dallas dispatcher 2 time has the slope of one. That means the recorder is on all the time. Well, that is not tremendous information. However, the purpose for doing this was to note with the stopwatch that at this time, as we listened to the tape, we hear the chief of police say, "We are approaching the triple underpass." And 19 seconds later on the stopwatch we heard him saying, "We are going to the hospital." It has been recorded that the chief of police heard the shots and he has testified that he had heard them. It is unlikely that he would give a routine position report after having heard them, so it can be presumed or we should presume that the assassination occurred sometime between those two voice transmissions by the the Police Chief. If one then goes over horizontally from that time estimate to our estimated correspondence of channel 2 time to stopwatch time we have our best estimate for the time of assassination, which is 12 seconds past 12:30.
Mr. CORNWELL - I now show you JFK exhibit F-365 and ask if you can identify that.
Dr. BARGER - This is the same kind of activity but conducted when listening to the sounds on the channel 1 tape.
Mr. CORNWELL - May we have JFK exhibit F-365 admitted into evidence, Mr, Chairman.
Chairman STOKES. Without objection, it may be entered into the record. [The information follows:]
JFK EXHIBIT F-365
Dr. BARGER - The purpose here is to determine at what time the impulsive sounds on channel 1 occurred to see if they were at the same time as the time of the assassination. Here is the time read on the stopwatch that is observed by the dispatcher on channel 1 in the Dallas Police Department which is a different clock than that observed by the dispatcher on channel 2. This is channel 1 dispatcher time; this is laboratory time measured with a stopwatch. This dispatcher was more talkative and the time annotations that he gave are more numerous--for example, he gave three time annotations at the time 12:26 and so we have mored at a here upon which to base a time estimate, using the least squares technique. The straight line indicates the result of that time estimate. There is nothing audible during this 5 1/2 minute period because mostly all you hear is motorcycle noise and so the channel 1 dispatcher made no time annotations there. However, before and after he did--and that gave us the possibility of forming the estimate for how his clock read them. We measured on the tape the time of the first impulsive sequence that we think may possibly be gunfire and we come over to our time estimate and down and find that we estimate the first impulse to have occurred at 12:30 and 47 seconds. Now, the estimate for the time of the first impulse then is about 35 seconds after the estimate of the assassination. If both dispatchers had been looking at the same clock, I would have had to conclude that the impulses on the tape would not pass this first screening test. In other words, the impulses occurred too late. On the other hand, each dispatcher was looking at a different clock. I have read in testimony in the Warren Commission report that the two clocks are not synchronized except once a month at the first of the month. This was the 22d. The two clocks were subsequently found by the FBI to be l minute off, so the variation in the times that we have discovered here is within the known accuracy of the two clocks. We have to conclude that the possibility that the impulses represent gunfire passed the first screening test; namely, that they apparently occurred at the time of the assassinations.
Mr. CORNWELL - So I take it then that the question of whether the impluses occur at approximately the time the shots were fired has been answered in the affirmative using a comparison of both channel 1 and channel 2.
Dr. BARGER. That is right.
Mr. CORNWELL - You have referred of course, throughout your testimony to the fact that it was a motorcycle which you believe had its button stuck and that, of course, according to the last exhibit and your previous testimony was a thing that caused the 5- minute gap or a continual transmission from that stuck button on channel 1. Is channel 1, however, the channel on which you would expect to find that type of motorcycle transmission?
Dr. BARGER - Channel 1 was the normal channel in use in Dallas. Channel 2 is used for special occasions such as the motorcycle at the head of the motorcade on channel 2. Some of those motorcycles near the limousine were known to have been switched to channel 2. On the other hand, listening to the voice communications on channel 2 at times before and after 12:30, I discovered the presence of the call numbers of several motorcycle policemen in the motorcade that were on channel 1.
Mr. CORNWELL - Moving next to the second screening test that you mentioned, namely, whether the impulses were unique, I would like to ask you if you would describe what you did to determine the answer to that question.
Dr. BARGER - Yes. We examined the full 234 linear feet of the waveform representing the output of the channel 1 recording when the button was stuck to see if there were any other impulsive patterns that occurred that were similar to these that we are looking at on channel 1. We found that there was one other sequence of impulsive events. It was dissimilar from the one we have looked at principally in that its timespan was less than 5 seconds. It occurred about a minute later than the period of impulses in question. We found no other impulsive patterns on the tape.
Mr. CORNWELL - So the answer to the second question is again in the affirmative?
Dr. BARGER - Yes.
Mr. CORNWELL - Going into test No. 3, which was the question of whether there was a timespan of at least 5 seconds, I would like to direct your attention to JFK exhibits F-336 A and B. These are exhibits that have already been admitted into evidence. Could you use them to illustrate your analysis with respect to the third test?
Dr. BARGER - . The impulsive events that we felt hypothetically might represent echo patterns began at approximately 137 seconds after the stuck button commences and continue through this portion at about 147 seconds. This period of impulses, this period, this period, and this period, represent four typical segments of the tape. The span between them is 10 seconds and that is more than 5.
Mr. CORNWELL - Now, with respect to test 4, that the impulses were of approximately the correct shape, how did you go about resolving that question?
Dr. BARGER - In this case we were familiar with the shape of transient waveforms generated by rifle fire and those were shown in the second exhibit. However, we saw that those waveforms did not appear in the tape that we were analyzing. We knew, however, that the loudness of the impulses from gunfire so near--well, anywhere in Dealey Plaza--would be so loud as to overload the radio, to exceed its capacity to transmit without distortion of the waveforms in question. In order to test whether the Dallas radio distorted the gunfire impulses in the way, or in the approximate way, that we see in these records, Mr. Robinson found a similar Motorola FM radio in use with the MDC Police in Massachusetts. He was able to test that radio by playing sounds of the Mannlicher-Carcano rifle, as tape recorded, electrically into its microphone connection, through an electronic circuit that mimicked the electro acoustical behavior of the microphone. He then went back to the receiver at the police station and made a recording of the distorted sounds that were in fact transmitted. The next exhibit illustrates those distorted waveform she measured.
Mr. CORNWELL. - I show you JFK exhibit F-368. As you just noted, that is an exhibit which would help you illustrate the techniques you have just described, is that correct?
Dr. BARGER - I anticipate that that will be the one.
Mr. CORNWELL. May we have JFK exhibit F-368 admitted into evidence, Mr. Chairman?
Chairman STOKES - Without objection, it may be entered into evidence at this point. [The information follows:]
JFK EXHIBIT F-368
Dr. BARGER - This illustration shows on the left side waveforms due to muzzle blasts and on the right side waveforms generated by shock waves from the Mannlicher rifle. In this photograph we see the waveform of a muzzle blast that was measured, with a good microphone, from a Mannlicher--Carcano. The amplitude of the muzzle blast is shown in time covering a total span on this illustration of 10 milliseconds. In this case we have the waveform, which is that sharp N shaped waveform shown that was measured from the shock wave of a bullet from a Mannlicher-Carcano, also on a scale covering 10 milliseconds. In this column we show the waveform transmitted by the radio to the receiver and subsequently analyzed at the receiver, as a function of the level of the loudness of the muzzle blast that was played into the radio; 139 decibels, very loud, 129, half as loud in terms of human response, 119, half again as loud, 109, half again as loud, 99, half again as loud. We see that the relatively simple shape of the muzzle blast waveform is made more confused by the radio. it oscillates more; it lasts longer in time and its shape in fact depends on how loud it was. The radio therefore was performing nonlinear distortion and compression on these waveforms at the levels indicated. Here the N wave coming in at 139 decibel level has a nice pristine N shaped waveform and comes out of the radio as a lower frequency oscillation. That is true even at a 10-decibel lower level, et cetera. But when you get down 30 decibels lower than this one, the radio now is capable of transmitting that waveform in an undistorted form.
Mr. CORNWELL - So we can see the basic distortion at different decibel levels. Do I understand that the various decibel levels are shown because they would correspond perhaps to different distances that the blast might be from a receiver such as a microphone?
Dr. BARGER - We have observed that the loudness of the muzzle blast waveforms during the test reconstruction in Dallas measured at the microphones closest to the rifle were 135 decibels, virtually the same as the loudest here. The loudest sounds measured at the most distant receivers were about 20 decibels lower than that, so the range of the loudest sounds is easily covered in this investigation. It shows that one cannot hope to identify, for example, the type of rifle fired by looking at the waveform; because the waveform that is characteristic of the rifle is severely distorted by the radio because it is too loud for the radio.
Mr. CORNWELL - I now would show you JFK exhibit F-369 and ask you if you can tell us what that is?
Dr. BARGER - This is a graph that quantifies, better for people who think in terms of graphs, the capacity of this radio not to accept and transmit loud sounds as efficiently as it transmits weak ones.
Mr. CORNWELL - Mr. Chairman, may we have JFK exhibit F-369 entered into the record?
Chairman STOKES - Without objection, it may be entered at this point
JFK EXHIBIT F-369
Dr. BARGER - Down here in decibels on this scale, increasing to the right, are the loudness of sounds introduced into the microphone. On this scale reading upwards are increasing loudnesses of sounds that are transmitted by the radio. These lines up in the region of loud sounds, where I said the levels of sounds in Dealey Plaza were, 109-139 decibels, are quite flat. In other words, if the loudness of the signals that were actually heard in Dealey Plaza were 30 decibels in range from the loudest to the softest, then, the loudness of the sound transmitted by the radio would only differ by 10 decibels. This is described as amplitude limitation. It would indicate that all of the loud and even the softer echos in the echo patterns at Dealey Plaza would have about the same loudness on the tape that was made after transmission through the radio. It was necessary to see if the radio caused this limitation, because this removes the subjective impression of gunfire from listening to these compressed sounds.
Mr. CORNWELL - Perhaps you could be seated at this point. I will ask you finally with respect to the final screening test No. 6, concerning the question of whether or not the number of impulses roughlycorresponded, what did you do to answer that question?
Mr. BARGER - We took a map of Dealey Plaza and calculated a rough approximation, using the mathematics of reflected, diffracted, and, scattered sounds, the number of echoes that we thought would be loud enough to audible over the noise of a motorcycle. We found there would be about 10 for a typical microphone location. Then we counted the number of impulses in each pattern of impluses that we see in the waveform records of the tape and we saw there were about 20. We realized there was still a possibility that these implusive sounds that we saw in the record of the tape were in fact caused by gunfire
Mr. CORNWELL - At this point then you had devised six screening tests, anyone of which I take it might have been sufficient to rule out these impulses as being gunshots, and they in fact passed all six tests, is that correct?
Dr. BARGER - Quite so.
Mr. CORNWELL - Now, at this point did you have any conclusions or, on the other hand, did you feel that further testing was required?
Dr. BARGER - At this point we felt we were justified in suggesting to the committee that a matched filter detection trial was warranted on the tape. As I said, the patterns that formed the basis for the match would have to be obtained by an acoustical reconstruction. The reason for suggesting the matched filter procedure for detecting the events was it is the most powerful method we know of with which to do that.
Mr. CORNWELL - How about telling us in just plain, common language what you are referring to when you say anacoustical reconstruction?
Dr. BARGER - The objective is to obtain echo patterns of the sort that I described briefly before, and the purpose for having these patterns is to become the basis of the match in the matched filter detector. In order to get these echo patterns, it was necessary to design a test that would get echo patterns that would in fact match with the events on the tape if in fact there were events on the tape that were gunfire.
Mr. CORNWELL - In other words, you suggested to the committee they go back to Dealey Plaza and fire a rifle there so you could record it and see exactly what it looked like in that urban environment?
Dr. BARGER - That is correct.
Mr. CORNWELL Before doing so, did you seek any independent opinion or consultation on this recommendation that you had made to the committee?
Dr. BARGER - Yes, we did. I think the committee felt that it would be wise for them to obtain a second opinion on the wisdom of conducting this test, and in order to do that they obtained the agreement of professors Mark Weiss and Ernest Aschkenasy oF Queens College to look at the results of our six screening tests that I just described and to look at our preliminary design for this echo pattern test or acoustical reconstruction and to form an opinion about whether they agreed with us that it was a reasonable and necessary thing to do
Mr. CORNWELL For the record, Mr. Chairman, Prof. Mark Weiss, whom Dr. Barger has just referred to, received a bachelor of electrical engineering degree from the City College of New York in 1952, and an M.S. in electrical engineering from Columbia in 1957. He has been a staff engineer at the Columbia University Electronics Research Laboratories and a project engineer and vice president for Acoustics Research at the Federal Scientific Corp. Currently, he is professor of computer science at the Queens College in the City University of New York. Mr. Weiss has written numerous scientific articles and technical reports. He is a fellow of the Acoustical Society of America and a member of the Institute of Electrical and Electronics Engineering. Mr. Weiss served on a panel of experts appointed to examine the Nixon-Watergate tape recordings during the grand jury investigation. The other individual Dr. Barger just referred to, Ernest Aschkenasy, received a bachelor of electrical engineering degree in 1967 and a master of electrical engineering degree in 1972, both from the City College of New York. He has been involved in the analysis and enhancement of acoustic signals for over 10 years and was an associate professor with Professor Weiss in the examination of the White House tape recording in 1974. He is currently a senior research associate in the Department of Computer Science of Queens College. Did Professor Weiss and Mr. Aschkenasy agree that testing in Dealey Plaza was a necessary and proper thing to do?
Dr. BARGER - Yes.
Mr. CORNWELL After consultation with the authorities of Dallas, Tex., the committee, of course, ultimately agreed that you should conduct the testing. What problems did you focus upon at this point in time that you would face in designing and conducting a valid test?
Dr. BARGER - If I may just make a comment before I answer that question, I remember something I was going to say before, that I forgot. In fact, I did not supervise the Judge Sirica panel that examined the tape recordings that President Nixon had made. Dr. Richard Bolt, of B.B. & N., did that. I happened to have been director of one of the divisions of the company in which some of that work was done. Now I remember your question, so I can answer it. The first problem that had to be solved in designing the test was the fact that we didn't know where the motorcycle was, if, in fact, it was there at all. The second problem was, although we had evidence about the type of rifle used that was fired from the Texas School Book Depository, we had no evidence about the alleged weapon that might have been on tthe knoll. For example, we didn't even know whether it was a rifle or a pistol. The allegation didn't include that information. We had to consider, also, where to put the targets at which to fire the bullets. As I have explained, the pattern of the N wave shed from the bullet is distinct, so the echo pattern at any one point depends upon the direction in which the rifle is pointing, as well as the place where it is fired from. So we need to decide where, in fact to fire the bullets. There was evidence the bullets, of course, had hit the limousine, the occupants in the limousine. There was evidence that a bullet had struck the curb on Main Street, down by the triple underpass, and there are the other indications by the presence of the impulses in the tape that there may have been a shot fired up near the corner of Houston and Elm, so we used those results to place the targets. The next problem we had to figure out was what ammunition to use; since the N waves are important. You have to have the muzzle velocity correct, and we needed to find ammunition that had a nearly similar muzzle velocity to that used by Oswald, or alleged to have been used by him. We had to consider as a matter of practical significance the amount of time it would take to conduct the acoustical reconstruction. Requiring live ammunition as it did, of course people had to be excluded from the area, and that can only be done for a short period of time. We had also to accommodate the listening tests that were conducted by Dr. Green, and which he will describe later.
Mr. CORNWELL - I would like to show you now JFK exhibit F-337. I would ask you if you could use that exhibit to illustrate how you solved some of the various problems in setting up the test you have just mentioned.
Dr. BARGER - Yes. This exhibit illustrates the portions of the microphones, the targets and everything else.
Mr. CORNWELL - Mr. Chairman, may we admit into evidence at this time JFK exhibit F-337?
Chairman STOKES. Without objection, it may be entered into the record at this point. [The information follows:]
JFK EXHIBIT F-337
Dr. BARGER - We positioned 12 microphones, as an array of microphones, in each of three positions: This group of 12; this group of 12; and this group of 12. The objective here was to cover all of the positions where the motorcycle may have been, and still expect to hear the sounds of gunfire in a dense enough way so that the echo patterns received on adjacent microphones would not be so different that no match could ever be achieved should the motorcycle have been halfway between two of them. The target locations that we selected, based on the evidence that I cited earlier, were here, No. 4; here is Zapruder frame location 313, target 3 at this point; and target 1 there. Rifles were fired from here [indicating the T.S.B.D.], as evidence indicates it was. A rifle and a pistol were fired from here [indicating the grassy knoll], as allegations have indicated there may have been.
Mr. CORNWELL - OK, when you say "from here and from here," simply for the record, you were pointing at that point to the Texas School book Depository as being where a rifle was fired from and the grassy knoll where both a pistol and a rifle were fired.
Dr. BARGER - That is correct.
Mr. CORNWELL - I would like to ask you now to look at JFK exhibit F-344 and tell us what this shows.
Dr. BARGER - This simply shows the sequence of shots executed for each microphone array position in turn.
Mr. CORNWELL - May we have JFK exhibit F-344 admitted into evidence, Mr. Chairman?
Chairman STOKES - Without objection, it may be entered into the evidence. [The information follows]
JFK EXHIBIT F-344
Dr. BARGER - Here are shown the four target locations. The first rifle position was in the depository, with the muzzle of the rifle in the plane of the window. Here the rifle was in the same position, but the muzzle was withdrawn 2 feet from the plane of the window. This was done because we had no clear evidence about where the muzzle, infact, was relative to the plane of the window, and that small difference makes a noticeable difference in the loudness of the muzzle blast as perceived in the plaza. The third location was from the knoll, firing with the rifle. The fourth was from the knoll firing with the pistol. The shot numbers here indicate the sequence in which the shots were fired and the absence of any number in any place indicates there was no correspondings hot fired.
Mr. CORNWELL Now, the numbers across the top where it says "No. 1, No. 2, No. 3," what does those correspond to?
Dr. BARGER - These correspond to the numbers of the targets, 1, 2, 3, 4, that were fired at.
Mr. CORNWELL - And the rifles which were used both from the window and from the grassy knoll were of what type?
Dr. BARGER - I am sorry; I missed that.
Mr. CORNWELL - The rifles which were used both from the Texas School book Depository and from the knoll were of what type?
Dr. BARGER - They were both of the Mannlicher Carcano type.
Mr. CORNWELL - And the pistol was of what type?
Dr. BARGER - It was a 38 caliber pistol, of what manufacture I don't remember.
Mr. CORNWELL - But the pistol would have been a subsonic weapon, is that correct?
Dr. BARGER - It was chosen to have a subsonic missile; that is correct.
Mr. CORNWELL - Then, if we were to read JFK exhibits F-344 and F-337 together, would it be accurate to state that the sequence of shots in each array was pursued in numerical sequence for each array of microphones indicated on the plot of the plaza.
Dr. BARGER - That is correct. The sequence indicated here was fired three times in repetition, once for each array location and each time ammunition of Norma manufacture was fired. The shot sequence was then repeated a fourth time when our recording equipment was recording the microphones in the third portion, with Western Cartridge Co. ammunition. This type of ammunition was of the same sort thought to have been used by Oswald.
Mr. CORNWELL - Why were the first 3 arrays of 12 shots--actually, 11 shots with a rifle; 1 with a pistol--why were they fired with Norma ammunition instead of Western Cartridge Co.?
Dr. BARGER - I understand that the Western Cartridge Co. ammunition of this type is no longer manufactured and is hard to obtain, and the committee could only get enough to fire through the sequence once; so Norma was used the rest of the time.
Mr. CORNWELL - So at least the results could be compared to see if there was any substantial difference between Norma and Western Cartridge Co.
Dr. BARGER - That is correct.
Mr. CORNWELL - Now, I would like to direct your attention to JFK exhibits F-339, F-340, F-341, and F-342.
Dr. BARGER - These are photographs that were taken during the period when we were setting up the acoustical reconstruction in Dallas.
Mr. CORNWELL May we have these four exhibits admitted into evidence, Mr. Chairman?
Chairman STOKES - Without objection, they may be entered into evidence. [The information follows:]
JFK EXHIBIT F-339
JFK EXHIBIT F-340
JFK EXHIBIT F-341
JFK EXHIBIT F-342
Dr. BARGER - This one shows a portion of Houston Street and all of Elm Street. The yellow x's on the street correspond to the position of the black dots on the previous exhibit and were where the microphones were placed. These sandbags that are observable here, barely observable here and there, are the first three of the four targets. The total number of sandbags available was insufficient to set up a fourth target simultaneously, so this pile of sandbags was transported to that location periodically.
Mr. CORNWELL - So the sandbag targets 3 and 4 were moved back and forth, and you pointed to the place.
Dr. BARGER - That is right. This photograph simply shows a ground level view of the microphones used to record the sounds at array position 3, and the sandbags with sand leaking out of them. So the experiment was problably over by that time. Here is a photograph from the knoll, looking up at the microphones in array position 3, and the sandbags. Here the marksman and his assistants are in the position where Oswald was thought to have fired.
Mr. CORNWELL - The very last exhibit you made reference to, of course, was taken on the sixth floor of the Texas Schoolbook Depository before the test began, is that correct?
Dr. BARGER. No; I am not sure when it was taken, but it was taken there.
Mr CORNWELL - Let me ask you this. At least during the testing the widows were closed down to the way they were in photographs taken about the time of the assassination, is that correct?
Dr. BARGER - That is a question I can testify about. It was known from the photographic evidence that during the period of the assassination the windows in the sixth floor were down with the exception of this one through which Oswald is thought to have fired, and it was halfway down. It was important to the accuracy of the reconstruction that all those windows be in that position exactly during the shots, and they were. However, it was a hot day and the people in this room opened the windows between shots to air themselves out.
Mr. CORNWELL - I now show you JFK exhibits F-358 and F-359.
Dr. BARGER - These appear to be aerial photographs of Dealey Plaza that would be quite recent, because they include several structures that were not there in 1963.
Mr. CORNWELL - May we have those admitted into evidence, Mr. Chairman?
Chairman STOKES - Without objection, they may be entered into evidence. [The information follows:]
JFK EXHIBIT F-358
JFK EXHIBIT F-359
Mr. CORNWELL - There is simply one part of those exhibits I would like to direct your attention to, Dr. Barger, and that is the very large new hotel structure which would appear somewhat to the south of the plaza. Would you tell us whether or not that, of course, was there the day that you did the testing?
Dr. BARGER - The echo patterns that we expected to receive and did, in fact, receive had a maximum time span of 1 second. There were other echoes that came in at later times that were very weak, so weak that they were not considered in any of the matches and could not have been represented on the DPD tape because they were so weak relative to the loud echoes. So, the only echo patterns we ever needed or used were never longer than 1 second. The time required for sound to travel from the depository to that structure and back is a little more than than 3 seconds, the echoes from that remote structure had no effect on the matching process what so ever.
Mr. CORNWELL - You then have indicated that the large structure was present on the day you did testing. It would not have been present, I take it, in 1963, but, nevertheless, it was so far removed from the plaza, that it would not have affect in any manner the results of the test.
Dr. BARGER - That is correct. It did not. Its echo came in much later than any of the echoes on the echo patterns that we used.
Mr. CORNWELL - What did you obtain from the testing?
Dr. BARGER - As a result of the four sequences of 12 - shot firings, we had 432 different test shot recordings on magnetic tape.
Mr. CORNWELL - Were they of the quality that you had hoped? Did the equipment function properly, et cetera?
Dr. BARGER - We monitored the recorded signals at the time that they were recorded to see if they were noise free and to see if they used the entire dynamic range of the recording system. In other words, to see that they were being recorded with the highest fidelity possible. We observed for each of those records that we had achieved that. We did no other analysis of the records at that time.
Mr. CORNWELL - I would like to now show you JFK exhibit F-338.
Dr. BARGER - This exhibit is an illustration of the test patterns, and it shows six of them.
Mr. CORNWELL - May we have JFK exhibit F-338 admitted into evidence, Mr. Chairman?
Chairman STOKES. Without objection. [The information follows:]
JFK EXHIBIT F-338
Dr. BARGER - Here we show six echo patterns in alternate array. They were generated by Western Cartridge Co. ammunition, which is somewhat incorrectly labeled here as Winchester ammunition, and then Norma for test shots fired from the depository with the muzzle 2 feet behind the plane of the window fired at target No. 3, received on microphones 7, 8, and 9 in array 3, namely, halfway down Elm Street. Time is plotted on the horizontal scale. From here to here we have the total time span of 1 second. We have the intensity of sound in decibels plotted on the vertical scale in each of the six graphs. We see initially a very loud pair of impulses; if you look very closely, you see there are two of those. The first of those is the shock wave of the bullet passing overhead. The second of those is the reflection of the shock wave from the street just below the microphone. Then there are three rather distinct echoes and several others here that you can see if your eyes are very good. This type of graphical data is on an ultraviolet recording, which is hard to photograph, but here is the arrival of the muzzle blast. It comes later than the arrival of the shock wave because the bullet is supersonic. Here is an echo in this case from the Records Building, and here almost nine-tenths of a second later is the echo from the Post Office Annex which is across Dealey Plaza. Now when you repeat that shot in every way except using Norma ammunition instead of Winchester, you see the same pattern. If you look at it in great detail, you find that the spacing between the shock wave and the muzzle blast using the Western ammunition versus that with the Norma is 5 percent greater. In otherwords, the bullet is 5 percent faster, giving a shockwave that occurs 5 percent sooner than the muzzle blast. That is an inconsequential time difference to the matching process, and is certainly not evident when looking at these records just with the eye. The similarty between these pairs of patterns which differ, only in the types of ammunition that were used, is very great, thereby establishing that the substitution of Norma ammunition for Western was an acceptable one. As one looks down farther in the street, one sees that these patterns change somewhat. For example, the strength of the Post Office Annex echo is a little bit larger at microphone 8 than it is at microphone 7, as an example.
Mr. CORNWELL Then, after determining that your test had gone well, that you got the type of data you were looking for, and that there was no substantial differences that would affect the vaildity of the test, depending on whether you used Norma or Western ammunition, what did you do next?
Dr. BARGER - The next project then was to begin the comparison of the test patterns with the impulse patterns on the police tape. Let me describe the process of doing this now. We first divided the motorcycle tape into segments, each containing at least one of those patterns of impulses that we were testing for the possibility that they were caused by gunfire. We then matched each of these 432 echo patterns that are exemplified by that exhibit with each of those 6 segments of the tape. Those six segments that we analyzed comprised the entire part of the record of the Dallas police tape that passed the six screening tests that I described. The procedure for conducting this match is a mathematic alone, and it is known as a correlation. The type of correlation that we used is a binary correlation, and this is a description of a fairly simple process, which I will now attempt to make entirely clear. The echo patterns were each examined to find the loudest echoes thereon, some patterns had only 5, others as many as 17. Any one echo that was loud enough to exceed the threshold of audibility was accepted. Then each of the six segments of the tape were examined, after having presented them in the same way, loudness in decibels on the vertical scale, and time on the horizontal scale. Those records were initially made at a horizontal scale of 16 inches equal to 1 second. Once those six segments of the tape had been thus prepared, they were similarly thresholded, and I will illustrate this more graphically in a minute, to determine all of the impulses on each that exceeded a threshold. They were then numbered, and their location in time was noted. Now the design of the test included the feature that each microphone was 18 feet from the next. It is possible that the motorcycle at any time was halfway between two microphones, so a microphone could at worst be 9 feet from the motorcycle if in fact there was a motorcycle present. That means that there is at least a 9-foot uncertainty in the location of the microphone with respect to where the motorcycle may have been at each time that we are examining. This was accommodated in our procedure by adding an uncertainty window 6 milliseconds on either side of each impulse found in the Dallas tape. In other words each impulse was considered to be 12 milliseconds wide, so as to include any echo received by a motorcycle that had been in fact anywhere it could have been with respect to the nearest microphone. The number of coincidences between impulses and echoes was the numerator, and the denominator was the square root of the product of the number of echoes by the number of impulses. If two patterns perfectly matched in this way, the cross-correlation coefficient that you obtained would be equal to unity. If they only matched at one point and at no other, it would be 0.1 or less. The bigger the value of the correlation coefficient, the better the match.
Mr. CORNWELL - The closer, in other words, that the number, which would be in percentages, point something, approaches one, the better the match?
Dr. BARGER.. That is correct. That was the procedure. Now once that was done, we had a big pailfull of 2,600 numbers, and we exhibited to ourselves then for the first time on the blackboard all of those numbers that were larger than a threshold value, which was set at 0.6. I will describe the reason for that in a moment. From this time on, I will mostly talk about those matches that exceeded a correlation coefficient of 0.6.
Mr. CORNWELL - I would like to show you JFK exhibit F-347, and ask you if you would tell us what that is.
Dr. BARGER - This illustrates two types of data. Here are three test patterns. These three test patterns were generated by a shot from the depository with the muzzle 2 feet behind the plane of the window and fired at the target No. 1, which was located just at the head of Elm Street in a position previously described, and it was received by microphones 4, 5, and 6 in the second array position. Those microphones were on Houston near Elm, and we see in each of these that the first sound that arrived was the muzzle blast. There is no shock wave that precedes the muzzle blast, and that is to be expected because in this case the shot is fired in this direction, and the microphone is over here, and according to the first exhibit I showed, the shock wave would not be seen 90(deg)laterally. As you look at the arrival of the muzzle blast, you see that in each channel it occurs progressively later in time, so that if you connect the peaks, they slant. This is because channel 4 microphone is father away from the rifle than is the channel 5 and channel 6 microphone. However, if you look at these peaks out here near one second, these are the echoes from the Post Office Annex. As the microphone moves away from the location of the rifle, it is moving toward the Post Office Annex. Therefore, the echo in fact comes in sooner, so when you connect the dots signifying each of those echoes, they have a slope in this direction. One selects all of the significant impulses on these test patterns. We have placed dots on them. Some of the dots are obscured in these dark areas where the photographer has overexposed them, but nevertheless, they are there. We have connected all of those that we think are caused by the same echo-generating device by lines, to show how the time that that echo arrives is changing continuously as you move the position of the receiver. Up here is shown a portion, a segment, of the Dallas police tape that was also prepared at the same time scale, 16 inches equals a second with intensity vertical on the scale in decibels. The threshold has been made, and all of those impulses that exceeded have been identified and numbered, and the plus or minus 6 milliseconds acceptance regions have been marked, these to accommodate the uncertainty of the exact position of the motorcycle. I am prepared to show how this echo pattern matches the test pattern--and I knew I would probably forget which one it is that matches with it, but it is quite evident. If you tried to match this pattern with this shot, the significant impulses at this point would not in fact match with the significant impulses in this pattern, even though with this setting the echo from the Post Office Annex does. However, if you match it with the test impluse obtained at channel 5 which is a different place, then they match quite admirably in fact. If you count the dots signifying significant echoes in the echo pattern with the marks signifying the significant impulses in the Dallas tape, you find there are 12 matches out of 17 possible impulses, and if you count these, 15 possible echoes. The cross correlation coefficient for that match is 0.75, above our threshold value of 0.6.
Mr. CORNWELL - Given the amount of noise in the Dallas Police Department tape, would you expect that you would ever get a complete match, all 17 out of 17 in this case?
Dr. BARGER - Many of the impulses on the tape, on the Dallas police tape, this segment of it in particular, that correspond to the total number that were above the threshold value of 17 are caused undoubtedly by nonacoustical events. Examples are the key transients that I described when I was showing the results of the spectrographic analysis. However, none of those impulses in this particular segment of the tape have been conclusively identified as being any of those. The noise from whatever its origin that is present in the police recording tape, there is demonstrably noise there, in addition to any impulses that may be caused by gunfire, those would rise up and compete with the impulses caused by gunfire and reduce the value of the correlation coefficient to some number less than one.
Mr. CORNWELL So in spite of the fact that the correlation coefficient was not one, the match was not perfect, your words were that this was a quite adequate match. In other words it had a correlation coefficient which approximate done; is that correct?
Dr. BARGER - Well, it was not possible to reach that judgment by looking at one alone. We looked at 2,600 of them, and reached our conclusions from that. This was to illustrate just one.
Mr. CORNWELL - Now I believe, Mr. Chairman, we forgot to ask that that last exhibit be admitted into evidence. May we do so at this time?
Chairman STOKES. Without objection, it maybe entered into the evidence at this time. [The information follows:]
JFK EXHIBIT F-347
Mr. CORNWELL I would now like to direct your attention to JFK exhibit F-367, and for your assistance ask that F-337 and F-344 be placed up there simultaneously.
Dr. BARGER - Yes. This one and this one have been introduced as evidence. This is new.
Mr. CORNWELL - Would you tell us what F-367 is?
Dr. BARGER - It is a list of those 15 matches that--of the 2,600 approximate matches we attempted--that did in fact exhibit a correlation coeffident higher than 0.6.
Mr. CORNWELL - May we have JFK exhibit F-367 admitted into evidence, Mr. Chairman?
Chairman STOKES - Without objection, it maybe entered into the evidence. [The information follows]
JFK EXHIBIT F-367
Dr. BARGER. Very well. There are 15 descriptors here. Each one describes a case where an acoustical test pattern matched better than the threshold value of 0.6 with a segment of the Dallas tape. The first situation where this occurred I will label with blue. There were four test patterns that corresponded with the segment of the tape that began at 137.7 seconds after the stuck button, with coefficient, correlation coefficient, larger than 0.6, and these are the four. I will note with a 1 that that is the first time in the tape that any of the test patterns correlated with any of the impulse patterns in the police tape with a score better than 0.6, and it occurred four times.
Mr. CORNWELL - So at that point you are telling us that there is a segment of the Dallas police tape which very closely approximates or at least has a correlation coefficient of over 0.6 with respect to the various test shots?
Dr. BARGER - Yes. This section may contain the sound of gunfire. Then going on down in the list, we have what I will label the second time, the second place on the Dallas tape where correlations or matches were achieved that were good enough to exceed the threshold value, and I will label that with red brackets to highlight it, and there were five of them. Then in the same way at a later time, around 145.15 seconds, in green, I will label and highlight the three test shot patterns that correlated with that part of the tape better than 0.6, and, finally, at 145 seconds--yellow is not the best, is it--well, the fourth part of the tape at 145.61 seconds had three different test patterns that achieved the correlation score greater than 0.6. Let me rummage through my briefcase and see if I can find another color. Black is the obvious choice. Now, a feature of a detection by a reciever that was designed to detect the possibility of otherwise subaudible events by using the threshold correlation procedure is that it can give threshold exceedences, the threshold having been 0.6, under two circumstances. One, it exceeds the threshold when it has correctly detected the event and the other is, it exceeds the threshold when it has incorrectly detected the event. The latter circumstance is called a false alarm.[Laughter.] It is the purpose of the rest of my testimony now to examine the question: Which, if any, are false alarms?
Mr. CORNWELL - Before you do that, I take it that you took each of the four segments of the Dallas Police Department tape, which you have indicated with the numbers 1, 2, 3, and 4, and compared them with all of the test patterns, and what you have simply illustrated on the chart is a match very similar to the one that you showed us physically how you performed earlier with respect to a shot in the first time frame. Is that correct?
Dr. BARGER - That is correct.
Mr. CORNWELL. Then would you use the exhibits which are presently in place and tell us what that means in terms of the other diagrams as to the location of the microphones and the direction and location of the shots.
Dr. BARGER - I can say a few preliminary things about that with these exhibits, a few preliminary things. The results suggest that there are detections at four different times of day. If the motorcycle were in Dealey Plaza, it would only be at one place at each of those times of day and would either be standing still or moving in some reasonable pattern. The correlations achieved, or the matches achieved, at the first time when any matches were achieved are either at microphone 5 or 6 in the second - array position. There are four correlations there, so that at this time on the tape, we would tentatively estimate that the motorcycle was there.
Mr. CORNWELL - Let me show you at this point then JFK exhibit F-370, and ask you if you would tell us what that is. Could we put the two exhibits, the latest one, F-370, over next to the----
Dr. BARGER - This would best be in this position I think, thank you. We want to examine now the meaning of these detections that passed the threshold level to see if there is any reason to believe that they are not all false alarms, possibly. I will attempt it in this way. The first time all day that we saw any matches was at this time which I have labeled in blue, and, the indication is internally fairly consistent, and it indicates that the location of the microphone at that time is between microphones 5 and 6. So I put a blue dot there because that location was derived from the matches made at the first time of day at which any matches were made, and then I will begin to construct a plot. It would be best if I could draw this for you if you didn't see what is already on there before I start, but if you will attempt to follow the pointer, I am going to plot here time of day with zero representing the time that this first occurrence was observed, and I am going to plot the distance down the motorcade route along the vertical scale as measured from the portion of the motorcycle at that time. In otherwords, 10 feet down the motorcade route, 20, 30, 40, 50, all the way down to here would be 250 feet. I will signify that I mean zero time and zero distance here by that blue circle. Congressman Fithian, will you let me get away with that? Shall I proceed? Very well. At the second time, 1.6 seconds later, when there were correlations that did in fact exceed the threshold, which I have labeled red, we plot the position of each of the microphones that are correlating with that sound on the tape. Some of them were up the street. So I will simply mark in red the time on this scale that corresponds to this time of this pattern, but I can't make a nice, little circle yet because they are all over the place. There must be some false alarms in there. All right now, at the third time we have green as an indication. Green occurs at this time 7 1/2 seconds after the time of the first one, which was indicated by blue. At the time of the green, the green part of the Dallas tape, we had three detections, three matches--one here, one here, one here. All those are not all in the same place and the motorcycle can only be at one place at the green time, as well as it can be only at one place at any other time, so there is a bit of ambiguity there, but let's press on. At the next time, which is one-half a second later, which would be indicated by the black time, 8 seconds after the first one, we notice that the portion of the microphone that gathered the test pattern that gave the correlation that passed the threshold was here, here, and here. All right, now I have explained where those 15 dots came from. Those 15 dots represent these 15 correlations that passed the threshold of 0.6, and they are illustrated as a function of the time when they occurred and the position down the street where the microphone was that picked up the test pattern that gave the correlations.
Mr. CORNWELL. May we have JFK exhibit F-370 entered into the record?
Chairman STOKES- Without objection, so ordered.
JFK EXHIBIT F-370
Dr. BARGER - Now, we look at these and immediately see the motorcycle can't be at all these places, but there is a high degree of order in this diagram. The negative hypothesis would be that the motorcycle was not in Dealey Plaza. If that were true, then this scale that describes the distance down the street of the motorcade would be meaningless in the data, and the data would occur in time and in distance down the street at random. But the eye can see that they tend to follow a sloping line. It can particularly see that because of these prior lines that I drew in. There is a lot of order in the occurrence of these 15 correlations. Now, how much order? Well, if one segments the position of microphones along the street into four bins, or four compartments, and segments the time at which they occurred into the four compartments that are naturally the four compartments into which the data are segmented, then one can question what is the likelihood that this ordered pattern could have occurred by chance. In other words was it likely this pattern would have occurred if the motorcycle wasn't there. There is a test for that sort of thing, and it is called the Chi square test. If you segment the data into four times and four places, as I have done, it is a test done with nine degrees of freedom. The Chi squared, value, which is a measure of order liness, is 17 1/2. For those of you that have tables of the Chi square distribution, the meaning of that number is this much order would occur only 5 times out of 100 if this was caused by chance. In other words if the motorcycle was not there and so the data were distributed at random, there is only a 5-percent chance that that would have occurred. This much order in the data suggests there is a 95-percent likelihood that the motorcycle was moving in the motorcade. That is just about at the level of statistical significance that gives a person confidence that there are correct detections in the data. On the other hand, there are demonstrably also false alarms. This can be seen by observing that if some of those correlations in fact, indicate the position of the motorcycle, then some of them must be wrong because the motorcycle can't be in two places at once. Mr. Cornwell, I could proceed with what I am doing now or we could put up those other three. I think it might be easier if I proceed.
Mr. CORNWELL - Go right ahead and proceed.
Dr. BARGER - It is now the task of the committee and me to try to identify the best we can which of these detections are false alarms and which ones are not. We have a good deal of confidence that many of them are not. Now, in order that the motorcycle could achieve this position 130 feet down the street from the blue position in the 1.6 seconds, it would have to go 55 miles an hour. There is no evidence to indicate that it did that, and so this particular detection is labeled a false alarm. It couldn't be true. It leaked through because we lowered our threshold of detection to the point where we had enough correlations so we could be reasonably certain that the true answers would emerge. We wouldn't want to shut them out. Now, if you assume that the trajectory of the motorcycle is from the blue position, at which we can be reasonably confident, through these, the slope of that line is 11 miles an hour. That is approximately the speed of the motorcade. If one said, perhaps these are false alarms and that is the correct trajectory of the motorcade, in that case the motorcade would be going 18 miles per hour approximately. It would be going from behind the limousine---I mean, 120 feet behind the limousine and drawing close to it. I had better explain what I mean by that right now. If we assume that one of these last two occurrences represents the so-called head shot, then we know at that time where the limousine was. It was at frame 313. Frame 313 is 250 feet down the street from the blue dot, so 250 feet at that time of occurrence is here, so this must be where the limousine was at that time. It was going at about 11 miles an hour as determined by photographic evidence. If one plots back at 11 miles an hour, one finds at the time of the first occurrence the limousine was somewhere 120 feet ahead of the motorcycle, which would have put it right there. Now, again, I am examining the question about whether these three or these three are candidates for false alarms. If these three seconds prior to the first impulsive pattern that we originally suspected could be caused by gunfire. There was no obvious explanation for that, until one sees that at that time the motorcycle was just beginning a 110(deg) turn, and on the inside track apparently, and he would therefore have to slow down to execute the turn. Now, it was further observed that the motorcycle sound stayed diminished after the turn. It did not increase to the level that it had formerly had. Therefore, it would seem that it couldn't have increased speed, which it would have had to do to achieve this position in 8 seconds. If on the other hand, it had continued at the same speed of the motorcade, it would have achieved this position in that time. There is, therefore, the diminished sound of the motorcycle that indicates that these are false alarms. Now, that is an example of the kind of corroborating or disqualifying evidence that is of nonacoustical origin. We are inferring that the motorcycle didn't speed up because the noise didn't increase, this allows us to identify as false alarms some of these correlations we have accepted by lowering the threshold sufficiently to catch the correct detections. In other words, indications of detection that were accepted by the test, but that were shown by other reasons not to be possible, are therefore, found to be false alarms. As a result of that judgment, the estimate of the motorcycle position at the time of the second impulse the red one, would be there, which is right there, and the estimated position then of the motorcycle at the time of the third occurrence, which is here, is right there. I lost my graphical symbolism a little, and that is fight there, and at the time of the last segment labeled No. 4, which at this time we would estimate it to be half way between those two right there, and that is there, 120 feet behind the limousine at the time of the head shot, if in fact these impulses represent the sound of the head shot. There is the possibility of labeling one of these four threshold crossings as a potential false alarm because it involves firing from this place at this target at the time that the limousine was here. That is almost 180 (deg) out. It is inconceivable that anyone would do that, and on that basis one of these can be judged a false alarm. The fact that some of those are thought to be correct detections was illustrated by all of the order in the data, as I explained earlier.
Mr. CORNWELL - Dr. Barger, does that conclude your description of the analysis that you performed?
Dr. BARGER - Yes, it does.
Mr. CORNWELL - Let me then ask you in sum, is it fair and accurate to state that after all of the analysis there is evidence of four shots on the Dallas Police Department tape, and that the acoustical sounds that may represent those shots are spaced as follows: between the first and second approximately 1.6 seconds, between the second and third approximately 5.9 seconds, and between the third and fourth approximately 0.5 of a second?
Dr. BARGER - Yes, that is a possible conclusion.
Mr. CORNWELL - I have no further questions. Thank you.
Chairman STOKES - Thank you very much. Doctor. I would just like to say you are a fascinating teacher. I am just glad I don't have to take a test on what you have taught us here, today. May I consult with the committee for just a moment regarding recessing at this time. At this time the committee will recess until 1:30 p.m. this afternoon. [Whereupon, at 12:15 p.m., the committee recessed, to reconvene at l:30 p.m., the same day.
Chairman STOKES. - The committee will come to order. The procedure this afternoon will be for the Chair to, first, recognize the gentleman from Indiana, Mr. Fithian, who will be permitted to consume such time as he may need in order to fully and extensively question the witness. After that, the Chair will operate under the 5-minute rule as to other members of the committee. The Chair at this time recognizes the gentleman from Indiana, Mr. Fithian.
Mr. FITHIAN - Thank you, Mr. Chairman. Dr. Barger, we want to thank you for your excellent, very technical, and very complete testimony this morning, And as you must be aware, this poses as very serious evidence for us in that it does not corroborate some other evidence that we have. And I want to go back now, so that I am clear and others in the room are clear, as to just what it was that you set out to ascertain by the tests that you ran in Dallas when you went back and sort of recreated the shot pattern. What was it that you were specifically trying to do?
TESTIMONY OF JAMES E. BARGER--Resumed
Dr. BARGER - Congressman Fithian, the first thing that we sought to do was to determine if there were any sounds of gunfire in Dealey Plaza that were recorded on that tape. In other words, we were seeking to determine if the motorcycle, whose stuck transmitter was transmitting sound, was in fact in Dealey Plaza.
Mr. FITHIAN - So you are trying to actually locate the motorcycle itself ?
Dr. BARGER - It became necessary, first, to determine if the motorcycle was in Dealey Plaza, and then to locate it there in.
Mr. FITHIAN - And as to its location, correct me if I am wrong, you set your microphones 10 feet apart?
Dr. BARGER - That is correct.
Mr. FITHIAN - And you did this from the beginning of the turn on to Houston, down Houston to the turn on Elm Street, and down Elm Street, at least as far as where the Zapruder film showed, the head shot to the President?
Dr. BARGER - That is correct.
Mr. FITHIAN - Now does this mean, to those of us who are laymen, that once you locate a match of echo patterns, you have physically located the motorcycle to somewhere within that 18-foot stretch?
Dr. BARGER - That is correct. The echo patterns depend for their structure on the location of the microphone that receives the sound. We sought matches of the echo patterns that were sufficiently precise to represent a motorcycle microphone located within approximately 9 feet of each of the microphones.
Mr. FITHIAN - And then you presumed that the motorcycle was moving at the speed of the motorcade, or roughly that?
Dr. BARGER - We presumed nothing about the location of the motorcycle or its speed or even direction of motion. The matches were made without any presumption what so ever about the position of the motorcycle, in fact, of course, without any knowledge that the motorcycle was even there. After having made the matches, however, the position, I should say, the location of the microphones through which we found matches did in fact progress down the motorcade route at the times that the four subsequent periods on the tape showed matches. And as I indicated previously, the locations of the microphones where the matches were found at the four different times were moving down the motorcade route at approximately 11 miles an hour.
Mr. FITHIAN - And the number of microphones you used was determined by what? By the uncertainty of where or if the motorcycle was there?
Dr. BARGER - We started out with no assumption about where the motorcycle was , other than the fact that it was presumed to be on the street along the motorcade route. Therefore, we wished to put microphones all along the route in Dealey Plaza. It was very difficult for us to record through more than 12 microphones at one time, and so in fact we did record through only 12 microphones at one time. It was rather time consuming to conduct the full round of test shots considering the need for observing safety precautions and the like. And so in order to conduct the entire test within a morning, we calculated that about 36 microphone locations could be accommodated and this indicated an 18-foot spacing. The 18-foot spacing was judged adequate because it would place the motorcycle no more than 9 feet from the nearest microphone. That dimension is about half the width of the street. So if we put the microphone in the center of the street, even though the motorcycle was at the curb, we would be within that 9 feet. The time it takes sound to travel 9 feet is 9 milliseconds. That is a fairly short period of time. We judged that small uncertainty, 9 milliseconds, to be adequately small compared with the total time over which the echoes would arrive, that being almost a thousand milliseconds, or 1 second. That is the way that we decided upon the 18-foot spacing, the desire to have a small enough error, possible error, due to uncertainty of the true motorcycle location and the desire not to conduct the test all day long.
Mr. FITHIAN - Then are you satisfied that the fixes, if we can use that term, of the motorcycle that you came up with, are within 8 to 10 feet, or something not much greater than half the distance between one microphone and another?
Dr. BARGER - Yes, yes, I am satisfied that the 18 - foot spacing was not too coarse.
Mr. FITHIAN - Now to the layman, it would seem that if you are going to recreate a test, that you might have wanted to use instead of the most modern microphone equipment, you might have wanted to use, as nearly as you could find, microphones and transmitters identical to those which you believed to have been on the original motorcycle. And I would like some explanation as to why you chose not to use the motorcycle microphone, which you have indicated at one point in your testimony you had indeed used, from the Massachusetts police. Evidently that kind of a microphone or transmitter is available. Why then did you use a more sophisticated system of microphones?
Dr. BARGER - A more sophisticated system?
Mr. FITHIAN - Yes, more sophisticated than obviously was on the stuck transmitter.
Dr. BARGER - Why did we use the more sophisticated?
Mr. FITHIAN - Why did you?
Dr. BARGER - There are two reasons. In the first place, as I showed, the radio distorts and limits the amplitude of loud sounds. Each radio does that in detail in a different way. We weren't seeking to look at the wave form of each sound echo, only the time at which it occurred. The radio does not distort the time at which it occurs, nor does the more sophisticated equipment that we used. The more sophisticated equipment that we used is known to be reliable and not to fail in times of stress in the middle of a sensitive test. Old motorcycle radios from those earlier days are known not to be very reliable, nor are they to be found in thequantities that we required. Therefore we selected a system that would give us equivalent data but more reliably.
Mr. FITHIAN - So that I understand now, the data that you were really looking for was not dependent upon the amplitude or the height of the blip, or what ever you want to call it, greater than a certain amount which would help you identify it. Rather you were trying to locate it along the time line?
Dr. BARGER - Correct. That is absolutely correct.
Mr. FITHIAN - As I understand it, Mr. Chairman, this committee employed two other specialists that Mr. Cornwell referred to this morning, Mark Weiss and Ernest Aschkenasy, and you went over the plan of the test with them; is that correct?
Dr. BARGER - That is correct.
Mr. FITHIAN - Did they concur in the layout of the array of microphones, the type of microphones? In other words, did they concur in your proposed test plan?
Dr. BARGER - They did.
Mr. FITHIAN - Tell me then something about the difference in the status of the science of acoutics from 1964, when presumably this tape was inexistence and could have been analyzed and 1978 when you analyzed it, 1977-78 when you analyzed it, not in great specificity. But what are the grand changes that have taken place in that 14-year period?
Dr. BARGER - Well, there are two. First, the adaptive filter that we used to reduce the level of the motorcycle noise on the tape was a procedure that was not then, had not then, been worked out. It was not known. Second, the method we used to detect for the possibility, to search for the possibility of sounds, is generally called a matched filter or a matched detector. The theory of that device, that method of seeking the presence of suspected signals in loud noise, was developed principally I believe by the radar community during World War II. It was therefore known in 1963 to people who study the process of detecting expected signals imbedded in loud noise. The community that shared that knowledge in 1963 was not as wide as it is now. I don't believe I knew about it then.
Mr. FITHIAN - But the filtering process that you used came in, I think you said this morning, in 1968 to 1970; is that correct?
Dr. BARGER - Well, probably more like 1966 to 1968, but, that is correct.
Mr. FITHIAN - Now some of the terms you used this morning I am sure must be every day terms to you, but I am not sure all of us followed those. One of the key terms seemed to be "impulsive events" or "sequence of impulsive events" or something to that effect. What does that term mean, to those of us who don't get along very well with this science?
Dr. BARGER - I used the term 'impulsive event" to describe the brief, loud bursts of noise that appeared on the Dallas police tape. Now when I listened to the tape, you hear spits and stutters and pops. Those would all be descriptors of impulsive acoustical events. When you look at the waveform as presented on the oscillographic records that I showed, then the transient events are characterized by short intervals of time in which the loudness of a sound is intense, so it looks like blips or peaks in the amplitude record.
Mr. FITHIAN - And another term that was used, I think, as you took that concept and tried to transfer it to the visual, was spectrographic analysis of this transient event. I take it that is that chart that you put upon the wall this morning?
Dr. BARGER - Yes, I did put--we did hhave an exhibit that was a spectrographic analysis of a segment of the tape recording; that is correct. Would you like me to discuss that briefly?
Mr. FITHIAN - I just wanted to make sure my understanding was correct, and, that is, that the spectrographic analysis is a sort of a visual playout of this grassy looking material that is blips and depressions.
Dr. BARGER - Yes; the spectrogram itself is a visual description of the tonal content frequency content, pitch content of sound as a function of time. In other words, if a person was raising his voice like that, you would see a diagonal line on the spectrogram, indicating as time progressed, the pitch of the sound was rising.
Mr. FITHIAN - And now the adaptive filtering you used, do I understand that correctly, that this is the process of filtering out noises and things that you don't want to measure?
Dr. BARGER - The adaptive filtering process, which I characterized as a Widrow-type adaptive filter was used because it is effective in reducing repetitive noises, not impulsive noises, but repetitive ones. If you listen to a motorcycle, basically you hear the sounds of the cylinders firing, and they fire at idle for that motorcycle about once every 140 milliseconds. So, therefore, the noise as generated by that motor cycle has a tendency to resemble itself every 140 milliseconds later. The adaptive filter studies that noise, determines what is expected to occur in the future, subtracts that out from the data that is just coming in, and leaves you with the absence of that repetitive noise. But if you are looking for transient events or impulses about which the filter could have no prior knowledge, because they only occur once, then that filter leaves you with those transients more clearly observable. The noises, in other words, the repetitive noise that was masking those transients is thus reduced.
Mr. FITHIAN - And one final sort of terminology question. You used the term "match filter technique" "matching filter techniques"
Dr. BARGER - Yes.
Mr. FITHIAN - [continuing].And that means what?
Dr. BARGER - That means that you have in your--you expect to receive one of many kinds of signals. By "many kinds,"I mean a signal in this case that has a series of impulses that occur in a definite sequence, like, let's say, the first one occurs at a particular time, the second one perhaps 3 milliseconds later, the third one maybe 15, the fourth one 27, the fifth one 12 1/2 after that, and so on, a definte sequence of impulses. We went to Dallas to find out what the sequence of impulses would be that would be generated by Dealey Plaza if a gun was fired. Having found out what that sequence of impulses is, you then go through the tape in question and look for sequences of impulses that match it. When you find one that matches it, you say aha, at that time something occurred that generated a pattern of transient events that just matches what we did in Dealey Plaza, and when that occurs, you judge that you have made a detection. You have identified a similar source of noise. The word "matched filter" is a technically correct or often used form, and the use of the word "match"is fairly self-evident, I believe.
Mr. FITHIAN - Now I am sure there must have been a reason for your lengthy analysis of this bell tone. I am not sure that--I guess my question is why did you look for and analyze and worry about the bell tone, since we were looking for some kind of rifle shots or pistol shots or whatever?
Dr. BARGER - There are two reasons. First, we wanted to see if in fact there were any sounds on the tape that were caused by acoustical signals such as a bell would generate. We found that the sound that resembled a bell was a bell. Second, we hoped to establish, we hoped to learn, where that bell really was and had thought if we could find it, we would then know where at least one microphone was that was transmitting on channel 1 at that time.
Mr. FITHIAN - So, you were trying to verify that there were transmittals on that tape?
Dr. BARGER - That there were acoustical events as opposed to what might be called microphonics. In other words, as you take a radio transmitter and just kick it around and shake it, as a motorcycle might do, particularly if the radio were broken, then it would transmit signals that wouldn't have any bearing due to sounds. We just wanted to see if there were sounds on there.
Mr. FITHIAN - Now, I am not sure, counsel, what the exhibit numbers are, but I am interested in the way you went about locating the targets; that is, physically locating the targets that you were going to fire at. I understand why you selected the two points from which you fired, but could you put up the three or four photographs of Dealey Plaza, F-367 and F-377?
Mr. CORNWELL - F-337 and F-344, I believe.
Mr. FITHIAN - While they are doing that, let me ask you sort of the central question. Is it your conclusion that you proved that there were four shots?
Dr. BARGER - No.
Mr. FITHIAN - With regard to the groupings of shots what do you prove then?
Dr. BARGER - As regards the grouping of the shots, we demonstrated with high confidence that if there are four shots, we demonstrated the times at which they occurred, and the intervals between them were described by Mr. Cornwell, 1.6 seconds, was it 5.9, and 0.5.
Mr. FITHIAN - Would you repeat that again, please?
Dr. BARGER - Yes.
Mr. FITHIAN - The distance, the time frame between the first and the second shot is what?
Dr. BARGER - 1.6 seconds.
Mr. FITHIAN - And between the second and what you perceived to be a possible third shot?
Dr. BARGER - 5.9.
Mr. FITHIAN - And between the possible third and the possible fourth shot?
Dr. BARGER - 0.5.
Mr. FITHIAN - 0.5?
Dr. BARGER - 0.5, one-half second.
Mr. FITHIAN - One-half second. So what you are saying, Doctor, is that if there were four shots fired, they came at those intervals?
Dr. BARGER - Yes.
Mr. FITHIAN - And let's hypothesize for a minute. If there were only three shots fired, how do you account for the disturbance that you find at I guess it would be 5.9 after the first shot--after the second shot, I am sorry.
Dr. BARGER - I don't have the best exhibit in front of me to answer that, but let me do it without the first time. Of the 15 detections that our matching process achieved, 10 of them cannot be discounted as false alarms. It would be necessary for at least three of those to be correct detections, to have established the coherence in the data that led to our conclusion that the microphone was in fact in Dealey Plaza. It is therefore likely that somewhere between 3 and 6 of the remaining 10 are also false alarm. Therefore, anyone---
Mr. FITHIAN - May I interrupt just a moment?
Dr. BARGER - Yes, of course.
Mr. FITHIAN - I think the staff was putting up the right pictures. I wanted the big pictures of Dealey Plaza. I think there are three or four of them altogether. You had three of them out just a moment ago. Go ahead, Doctor.
Dr. BARGER - Therefore, it would not be unreasonable to expect that approximately 5 of the remaining 10 correlations were also false alarms. That would indicate that about one-half of the detections that I did not previously indicate to be false alarms, about one-half the remaining 10, are false alarms. This would indicate that the probability that each one is a correct detection is about one-half.
Mr. FITHIAN - I am going to return to this a little bit later. I am going to put those microphone images up there and we are going to go through that time frame because it is very important to me, but right now I want to try to establish the location of the targets. Now, I am not at all interested in the charts fight at the moment, I just want the pictures, the two pictures you have plus another one that shows some interstate signs with targets behind them. That is the particular one I want. [Exhibits F-339, F-340, F-341, and F-342 were displayed.]
Dr. BARGER - Well, it is there.
Mr. FITHIAN - Yes, OK. Set it up on the upper easel if you will. Thank you. Now, could you put on your Lavalier microphone, Doctor, and I would like for you to locate for us again the locations of the targets that they fired at.
Dr. BARGER - Yes; the target that was illustrated as target location No. list his pile of sandbags right here.
Mr. FITHIAN - And let me just make sure my optical illusion isn't getting away from me. That is between the Texas School Book Depository window on the left and the interstate signs overhead, is that correct?
Dr. BARGER - This picture is taken from the window adjacent to the window from which Oswald is thought to have fired, so it is taken from the depository.
Mr. FITHIAN - So that one you are pointing at is up the hill, if you will. It is located in the road prior--if you are going toward the underpass--prior to arriving at the interstate signs, the first target that you just had pointed at down here, just right there.
Dr. BARGER - Yes.
Mr. FITHIAN - That is physically before you get to the interstate signs.
Dr. BARGER - These signs?
Mr. FITHIAN - Yes.
Dr. BARGER - Well, it is physically just before them, that is correct.
Mr. FITHIAN - And the second target is where?
Dr. BARGER - The second target is hiding behind the trees right at that point.
Mr. FITHIAN - The third target is the one down the road?
Dr. BARGER - That is the third target.
Mr. FITHIAN - Now, in the location of targets, are those, as nearly as you can compute from the Zapruder film or otherwise, the exact location of the President and Governor Connally in the limousine?
Dr. BARGER - No; with regard to target No. 3, which was positioned to be at the same place as the limousine in frame 313, it was put in that place as well as we could determine it.
Mr. FITHIAN - And is target No. 1 in the same location that you presumed the first shot was fired?
Dr. BARGER - Of course, I don't know exactly where the limousine was when the first shot was fired.
Mr. FITHIAN - I guess basically I am asking you why did you locate the target there?
Dr. BARGER - As I recall, we sought to place the first target at about the position of the limousine, at about frame 158-160. The reason for that was that the preliminary screening that I described earlier of the impulses on the tape, indicated that if the first pattern of impulses that could be seen occurred prior to frame 313 by enough time to place it back at about frame 158. That is why we tried to position the target at that place.
Mr. FITHIAN - Is target No. 2--which doesn't really show up from here, but you pointed to it--is that at as nearly an accurate location as possible?
Dr. BARGER - May I ask Mr. Cornwell a question?
Mr. FITHIAN - Yes.
Dr. BARGER - I forget right now which Zapruder frame we tried to position target No. 2 at.
Mr. CORNWELL - We initially attempted to place it in the vicinity of 190, which would have been slightly further down the street from where it ultimately ended up, but the tree size is different today than it was in 1963, and the signs over the street which are in that area were of course not there in 1963, so we had to simply find the shortest point from the 190 frame that we could still shoot at sandbags. It was moved, as I recall----
Dr. BARGER - We were striving for the location of the target at the position of the limousine in frame 190, which was obscured by the new growth of the tree, and so we moved it to that position to make it---
Mr. FITHIAN - Doctor. the reason that I am going into this is that in studying the data last night from your research, and going over what you find as possible matches and then eliminating those which you believe to be false signals, there seemed a dirth of any matches with the second target in your data. The question is whether or not there is anything--we have already eliminated the new hotel building several blocks away as having been in any way altering the echo pattern. I am curious to know whether or not the location of that target, the interstate signs, the firing direction or anything like that would tend to give us the kind of data that we seem to have on target No. 2.
Dr. BARGER - Three of the matches were achieved for test patterns obtained by firing at target No. 2. I wouldn't describe that as a dirth, that is to say, three out of 15 would represent.
Mr. FITHIAN - But if I may come back to this a little bit later, if you want to remember the point and we will take it up then. If I remember in going through the ones that you eliminate as false alarms, that reduces any match to target No. 2 either to one or to zero, I am not positive, but we will come back to that. I just was curious to know whether the intrusion of the interstate signs into the whole acoustical pattern does anything to the results you get.
Dr. BARGER - Yes; the target No. 2 was responsible for at least two false alarms. Let me just check this a moment and make sure. Yes, it contributed false alarms in each case. There was a detection made at the second time interval when a shot was fired at target No. 2, and that one was eliminated because it was detected at microphone No. 5 in the third army position, and that was the one that would have required a 55-mile-an-hour speed of the motorcycle to achieve, and so that was labeled as a false alarm. Target No. 2 contributed a false alarm here, which was one of the three detections made at the third time segment. That too is ruled out because of improbable motorcycle speed required to achieve that position at microphone No. 7 at the time of the third group of matches. And finally, a shot at target location No. 2, contributed a false alarm in the fourth pattern, that one having been identified as a false alarm by the improbable motion of the motorcycle required to achieve it, so that is correct. The three detections that were achieved from test patterns obtained by shooting at target No. 2 appear to be false alarms.
Mr. FITHIAN - What impact, if any, did the firing of the bullet from the school depository window between the two interstate signs, what impact would that have in altering the data, if any?
Dr. BARGER - The presence of a structure such as this would have been highly irrelevant to the tests had it been over here.
Mr. FITHIAN - You say "highly relevant"?
Dr. BARGER - Irrelevant.
Mr. FITHIAN - Irrelevant.
Dr. BARGER. Had it been over here. The fact that the trajectory of the bullet missed that sign by only a few feet indicates that, as the shock wave which is radiated from the bullet as it passes would be in fact scattered by those signs, generating a new source of sound at that point.
Mr. FITHIAN - And so then you really couldn't expect to get a match up; is that what you are saying?
Dr. BARGER - That would introduce additional echoes in the test pattern that would not have----
Mr. FITHIAN - Let me make sure I am correct. If you introduce additional echoes or if you get additional echoes anywhere that don't match up, that reduces the probability, re duces it from eight to seven or seven to six or six to five or whatever.
Dr. BARGER. It reduces the probability of detection and it increases the likelihood of a false alarm.
Mr. FITHIAN - Thank you. Now I also looked at the pattern of shooting and noticed that you did not have as many shots from the grassy knoll toward No. 2 as at the other targets. I think No. 1 and No. 2, if I am not mistaken. Were there any reasons why you didn't have a full round of firing?
Dr. BARGER. Yes; I think you are referring to the fact that we did not fire at target No. l from the knoll.
Mr. FITHIAN - I am sorry, I said two. I meant one.
Dr. BARGER. Yes.
Mr. FITHIAN, Yes.
Dr. BARGER. That is correct. When we were setting up the locations of the microphones and the rifles and soon, we observed that target No. 1 was directly between the rifle on the knoll and the spectators that had been positioned behind a barricade on Elm Street, and it was judged entirely inappropriate to attempt that shot.
Mr. FITHIAN - Now there is one other question I need to ask about what is up on the board there on the easel. When we visited Dallas, when the committee visited Dallas, and we inspected the Texas School Book Depository, we were told that, at the time that they picked up the shells, the empty cartridges on the sixth floor near the corner, I believe it would be about where the gentleman is standing or in that area, that the area was physically cased in by boxes, not quite entirely, but nearly so, and that some writers have described this as the snipers nest, et cetera. But in any event, to get to the acoustics of it, would those stack of boxes in the depository right around where allegedly the shots were fired have any significant impact on the echo pattern that you could expect to get outside?
Dr. BARGER - They would not have a significant impact on the matches performed with the echo patterns. The reason is they would introduce into the echo patterns additional signals which are reflected from the boxes you describe that occur at a time later than the muzzle blast. By the time it takes the sound to go from the muzzle to those boxes and back out the window, that amount of time would be less than 12 milliseconds, if those boxes were within 6 feet of the rifle. And we have, as I described, broadened the width in time of each impulse on the motorcycle tape by 12 milliseconds to accommodate the uncertainty of microphone position relative to the motorcycle. And the broadening of the acceptance time for each impulse in the motorcycle tape solves the uncertainty caused by the lack of precise microphone location, since we didn't know where the motorcycle was. It also solves the problem that you just described.
Mr. FITHIAN - Let me see if I understand that now. What you are saying is because the little elliptical bins that you put over these blips-- I don't use very scientific language here-- but that you put over these blips in the spectrograph because they accommodated up to, what did you say, 6 feet on either side?
Dr. BARGER - Yes, 12 in total.
Mr. FITHIAN - Twelve feet total, that the boxes in order to have been in anyway effective would have had to have been closer? In other words, your accommodation, your allowance, took in any allowance for the boxes being there or not being there?
Dr. BARGER - Yes, providing those boxes were within 6 feet of the muzzle. If they were significantly farther than that, then the echo coming from them and trying to get back out of the window and there by becoming relevant to the test pattern would be so weakened so that it wouldn't have had any significance either.
Mr. FITHIAN - For practical matters, you are saying it doesn't make any difference whether you stack up boxes when you do the test firing or not?
Dr. BARGER - Absolutely.
Mr. FITHIAN - Thank you. Let the record show that the question pertained to JFK exhibit F-342, the picture of the marksman. Now one thing that has been bothering me this morning is the possibility that since more than one radio could be transmitting on that channel 1 that the stuck microphone was on, that indeed we might have been picking up some sounds from somewhere out of Dealey Plaza or somewhere else by some microphone other than the stuck microphone, since I believe you said that the bell tone was off outside. The bell tone did not come in over this particular microphone----
Dr. BARGER - That is right.
Mr. FITHIAN [continuing]. To anyway that we could locate. Then why couldn't we hypothesize that perhaps the third or the fourth shot or the first or the second shot or some other shot might indeed have been picked up, that kind of a sound might in deed have been picked up by some other radio transmitter being keyed somewhere else other than Dealey Plaza?
Dr. BARGER - Yes; we did establish, particularly with the spectrograms, that other microphones were keying in particularly at the times, the later two times, according to time three in green and four in black on that exhibit. And so during the time when those other radios were transmitting, sounds from their microphones would be expected to also appear in the tape recording, and, therefore, in a pattern of impulses was generated by some mechanism at the location of the other microphone, then that pattern too would appear on the recorded sound. However, these patterns were quite complex. they contained no fewer than 10 echos, as I recall, spread over total times no less than about half a minute--let me see now, half a second--and the interval of time between each of these 10 echoes over this whole period of time, half a second or more, is a very intricate pattern. The likelihood that some other mechanism that would generate a similar pattern that would match with the test patterns is extremely remote.
Mr. FITHIAN - And if one of the other microphones were on one of the other motorcycles in Dealey Plaza what then?
Dr. BARGER - If another motorcycle in Dealey Plaza keyed in at that time, you would have a test pattern, if you will, that is to say, you would have the sound of gunfire on that one too. If it was sufficiently noise free that our detection process caught it, it would have shown a high value of correlation in the match and would have been marked as a detection.
Mr. FITHIAN - But it would have come the same time frame, though, if it were a shot in Dealey Plaza; is that correct?
Dr. BARGER - That is correct.
Mr. FITHIAN - And so the only thing that would be somehow altered would be the location of the motorcycle.
Dr. BARGER - That is correct.
Mr. FITHIAN - So what you are saying is that the only way you could have gotten the pattern that matched is if over some other transmitter that was not in Dealey Plaza to get those 10 or 15 or how ever many echo patterns matched up, there would have had to be a configuration somewhere else very much like Dealey Plaza. The transmitter would have had to have been keyed at exactly the right time, and then you would have had this---
Dr. BARGER - That is correct.
Mr. FITHIAN - How would you classify that; very unlikely, impossible, remote?
Dr. BARGER - Extremely unlikely.
Mr. FITHIAN - When you went to Dealey Plaza, you expected a certain approximation or a certain number of impulses. In general now, not referring to anything specific, but your general conclusion, did you get the approximate number of impulses that you anticipated?
Dr. BARGER - Yes, with the term you used, "correlation coefficient," when you got those. Would the correlation coefficient be altered if the motorcycle is not at the exact location of the test microphone? In other words, you talked about a correlation coefficient of 0.8 or 0.7, 0.75, 0.6. Would that have been altered if the location of the microphone correlation occurring if you by chance did not have the microphone in exactly the right place. If you insisted that those impulses line up with those echoes precisely, you would have to have the motorcycle just where the microphone was. We didn't have that many microphones or that much time, and so we used, as I said, the 18 foot spacing of microphones. In order to prevent a loss, a significant loss of correlation, because of the uncertainty with respect to the location of the motorcycle and the microphone, we accepted anything that came within 6 milliseconds as a match. Now let me explain where 6 milliseconds came from. I was trying to guard against low values of correlation, and therefore loss of information, just because I happened to miss the location of the motorcycle, but I couldn't accept as a match echoes and impulses that were half a second apart because then I would accept everything, so it is necessary to find a medium ground. Now here is how that was done. In the case where the microphone and the reflect or that is causing the echo and the source are all in one line, then the 9-foot uncertainty that I had with the 18 foot spacing, plus or minus 9 feet, would generate a plus or minus 9-millisecond uncertainty in the location of the echo. Now it is also true that if the sound that generates the echo that I am interested in is arriving perpendicularly to the line connecting the microphone and the possible place of the motorcycle, then that uncertainty is of no consequence because it would arrive at both of the two places at the same time. So the error caused by this phenomenon varies between zero and 9 milliseconds. So mathematically we said the arrival of these echo sounds from each direction is equally likely, and we determined an average of the error that would be introduced by a 9-foot uncertainty, and it was 6 milliseconds. This is not a linear average. That would have given 4 1/2, but there is a cosine involved in this, and so the 6-millisecond uncertainty was arrived at in that way, and it was designed to minimize the loss of correlation due to uncertainty in the microphone location. However, it won't work perfectly because in those cases where the error is actually 9 milliseconds, when the echo happens to be coming in in the same direction as the line connecting the motorcycle and microphone, then it will cause a lack, a loss of correlation. So the answer to your question is there is a slight loss in correlation but it is not as large as it would have been if we had not used the plus or minus 6-millisecond window.
Mr. FITHIAN - Staying with the loss of correlation, because some of us are bothered when you match up a shot pattern that we know happened, and you can't match up all the 12 blips or the 15 blips or whatever, here and there, what you have just said is that some of them might be attributable to the fact that the motorcycle was outside by 3 feet or whatever. In other words, you might get a reduction in the correlation coefficient because the motorcycle is just beyond your tolerance level. Second
Dr. BARGER - That is right.
Mr. FITHIAN - Would you get a reduction in the correlation coefficient if induced onto the tape by a second transmitter somewhere there were noises that exceeded the threshold level that you established?
Dr. BARGER - Absolutely. The presence of impulses in the motorcycle tape that we counted, because we observed them robe there, that are caused by nonacoustical effects, give us therefore the impossibility of achieving a match because they were caused by some entirely different phenomenon. And the way of computing the cross correlation coefficient or the correlation coefficient that accommodates that, in other words, in the denominator is the square root of the number of impulses. If there is a lot of noise in the tape, as there is a good deal, and many of those impulses are caused by that, they can't be matched, and they will reduce the level of the correlation coefficient just mechanically, because there are numbers in the denominator. So if there are lots of noise pulses, that will reduce the correlation coefficient, exactly.
Mr. FITHIAN - So you would not expect to get a one, or I think you used the term "unity."
Dr. BARGER - The motorcycle tape is so noisy, not only with the sound of the motorcycle, but also keying transients and the like from other transmitters that it would be extremely unlikely that you would have a segment of the tape so noise free that a perfect correlation would be achieved, and in fact none were.
Mr. FITHIAN - From what you know about the echo pattern of the Mannlicher-Carcano rifle, what insight if any, can you offer into Governor Connally's testimony, if you heard it or read it? Let me try to reconstruct. Do we have the transcript of Governor Connally? On September 6, Governor Connally testified and said that--let me back up here a little ways. Let me take his last part of his testimony first. He says, "I heard another shot. I heard it hit. It hit with a very pronounced impact," and at that point the Governor slapped his hands together to demonstrate the sound that he heard. "Almost like that."He said" It made a very, very strong sound." Then he says: Immediately I could see blood and brain tissue all over the interior of the car and all over our clothes. We were both covered with brain tissue * * * And he goes on. Now, as I interpret what the Governor said, after he had been hit, and Mrs. Connally had pulled him down into her lap, he was still conscious, and he heard what sounded like a shot, and then heard what sounded like the bullet striking the Presidents head. Now, No. 1, if in fact the speed of the bullet is supersonic, you could not hear it in that sequence; am I correct?
Dr. BARGER - That is correct.
Mr. FITHIAN - In other words, he would have had to have heard the bullet striking the skull first, and then the muzzle blast would come at some fraction of time after that?
Dr. BARGER - That is correct.
Mr. FITHIAN - Well, then, obviously there has to be some other interpretation of those sounds, if in fact the Governor heard the sounds correctly. Can you shed any light on this at all?
Dr. BARGER - Yes; the findings, as I have described them, are that if there are four shots, they have the sequences that we described, and in fact, if you could uncover that back chart, please, you will see that the time segment marked in green occurs a half a second before the time segment marked in black. Therefore, if there are four shots the times that they occur are shown there on that chart, the last two being a half a second apart. Now, as I indiated, there are false alarms in this detection experiment or test that I have conducted, and so, therefore, it is the purpose of other evidence to compare to these findings to see which--if you can determine which of these findings are, in fact, corroborated or are discredited by other evidence. In that sense, the comment that former Governor Connally made is of some relevance because a statement that two loud sounds were heard, that are separated only by a small period of time--I don't remember exactly what word he used--'shortly thereafter,' as I recall-would indicate that he heard two loud impulsive sounds at the time of the third shot. I can't put any significance in the fact that he may have inverted the two times. That was a traumatic period, obviously, for him. But it is interesting that he did, in fact, characterize as the sound of impact what must have been the sound of a rifle, because it would seem possible, then, that his testimony indicated there were two briefly separated impulsive sounds that might both have been shots.
Mr. FITHIAN - I agree with you obviously that it was a very traumatic and almost impossible-to-imagine state of mind. But, I recall the Governor saying very clearly, early on, that he had done enough hunting that he recognized rifle shots when he heard them, et cetera, and that is what caused him to turn his head at the beginning way back, I don't know, frame 170 or 180, or whatever, and he did characterize or if there are only three shots and the last one is the one that hit the President in the head, then he had to confuse what would have been a bullet wound in the skull with a rifle shot.
Dr. BARGER - That is correct.
Mr. FITHIAN - As an expert in acoustics, can you just help me out in trying to distinguish what the differences in characteristics would have been? Going back to my original premise of the question, the first thing he heard after being in Mrs. Connally's lap could not have been a rifle shot if there is only one shot fired.
Dr. BARGER - That is right.
Mr. FITHIAN - The first sounded to him--if you x out our fourth one or third one you have come out with as a possibility, prior to the head shot, then that first noise the Governor heard could not have been a rifle shot.
Dr. BARGER - If he could have heard the sound of the impact at all, as he thought he did, then it could not have been the second sound that he heard; it would have had to have been the first-what he described as an impact.
Mr. FITHIAN - My question was basically if you could help me describe acoustically or otherwise what the human ear would hear in the difference between a rifle shot from the Texas School Book Depository and a bullet striking the head of the President 6 feet away or 5 feet away or what ever.
Dr. BARGER - I have heard the former, and, of course, I have no concept of the impact sound, I really have no opinion on that.
Mr. FITHIAN - I want to return to that troublesome shot from the grassy knoll, the third one that comes just ahead of the obvious head shot. If we are to stay with three bullets being fired as our final interpretation, then we have to somehow or other rationalize a way or do away with or accept as other phenomena the third impulse that you have on your charts, is that correct?
Dr. BARGER - That is correct.
Mr. FITHIAN - What might the third impulse be, then, if it isn't a shot?
Dr. BARGER - If it is a false alarm, which I described as the alternative to being a correct detection, by the very nature of a false alarm, it cannot be very easily explained. The only reliable procedure I can conceive of for identifying it as a false alarm is by comparing the time that it had to have occurred with all other testimony that has come and will follow about the possibility of that having occurred.
Mr. FITHIAN - Random statistical errors? Would that have done it?
Dr. BARGER - As I indicated just before, I think there is an even chance that about half of those remaining detections are, in fact, false alarms. Each one has an even probability of being one, including the one you just cited. I guess there is a chance of random error that that correlation occurred.
Mr. FITHIAN - I would like to recall, Mr. Chairman, JFK exhibit F-370. Doctor, if you would proceed over there, I want to make sure before I turn you loose here that I understand that vital chart. Now, starting from the lower left-hand corner, where originally on the chart you had four possible verifications, and you eliminated one, you are fairly certain that that is the first shot, and you are fairly certain of the location of the motorcycle within 10 feet; is that correct?
Dr. BARGER - The origin of this chart represents the estimate that the motorcycle was half-way between microphones 5 and 6 at that time; that is correct.
Mr. FITHIAN - Now, you use the term "false alarm." Perhaps we should put up JFK F-367 there for you to refer to. I notice in some of those that you rule out as false alarms they are really the same shot except that one is with the muzzle at the plane of the window and the other is at the muzzle 2 feet inside. Isn't that correct?
Dr. BARGER. - There were these two which you must be referfing to.
Mr. FITHIAN - Take No. l, for example.
Dr. BARGER - This one?
Mr. FITHIAN - Yes; which one have you eliminated--one of them you have eliminated. But is it meant that the first shot heard would have been from the grassy knoll and it would have been aimed at the target clear down by the underpass, is that correct?
Dr. BARGER - That is correct.
Mr. FITHIAN - So you eliminated that just because it wasn't very probable that the first shot would have been it was 75(deg) away from where the limousine was, or what ever?
Dr. BARGER - That is correct. I used that as an example of the lack of any evidence to corroborate that someone would have done that.
Mr. FITHIAN - That leaves three other matches or verifications you came up with right in that time frame?
Dr. BARGER - Yes.
Mr. FITHIAN - As I read this chart, two of those are shots which were fired with everything exactly the same except that the rifle muzzle was withdrawn 2 feet from the plane of the window.
Dr. BARGER - That is correct.
Mr. FITHIAN - And so, in fact, all three of those matches come from the microphone being in the sameplace and everything else being in the same place with the exception that you fired one, which is shot No. 3, which has an 0.8 correlation coefficient, with the muzzle at the window plane, and you fired the other two, having 0.8 and 0.7 correlation coefficients, with the muzzle of the Mannlicher-Carcano withdrawn inside the window 2 feet. That is the only difference, isn't it?
Dr. BARGER - That is correct apart from the fact that--
Mr. FITHIAN - I am trying to account for all these extra dots, because to the average person looking at that, it looks like there are 15 different shots and obviously that is not the case. We are trying to match up signals from repeated tests, and your verifications come up with four of those being possibly correct, and you eliminate one as being highly improbable.
Dr. BARGER - Yes.
Mr. FITHIAN - But the other three are all from a Mannlicher-Carcano shot from the window into the target.
Dr. BARGER - Yes.
Mr. FITHIAN - As you move on over about 1 1/2 seconds we see another group of shots which you have marked with a red circle.
Dr. BARGER - That is correct. These are marked here and listed in this table.
Mr. FITHIAN - As I take it, there are possibly four matches in that area. You have ruled out the one from the knoll at the target No. 2. The remaining four, again, are fired from the same place, the only difference being that two of them are with the muzzle withdrawn and two of them are with the muzzle at the plane of the window.
Dr. BARGER - That is correct.
Mr. FITHIAN - So, again, then we are not really talking about a different variety of shot impulses on the original tape. These are shot imputes you put on the test tape because you fired several times, isn't that correct?
Dr. BARGER - That is correct.
Mr. FITHIAN - And the reason they show up at that time frame match would be because on the original tape that is when the second shot was fired. Is that correct?
Dr. BARGER - That is very close to correct. These indicate where on the original tape is the pattern of impulses that looks like the test shots.
Mr. FITHIAN - Now you are aware that the FBI test firing by the expert indicated you couldn't fire the MANNLICHER-CARANO more rapidly than 2.25 or 2.30 seconds. That much time had to separate shots. You are aware of that testimony in the Warren Commission.
Dr. BARGER - As it turns out--I am aware of that and was . However, I had no reason to put high reliability on that, and I could not allow that to influence the interpretation of the results.
Is that correct?
Dr. BARGER - Yes; I felt confident in ruling this one out, because I was certain there was no motorcycle going 55 miles an hour. On the other hand, the fact that all of these correlations came up 1.6 seconds later is the way the test developed, and that is the result that was obtained.
Mr. FITHIAN - I want to make sure I also understand, when you look down in that lower left-hand corner, near the red circle, you have two dots below and two dots roughly above the imagined track of the motorcycle, but, again, during the same time frame-from here it looks like that might not be the case--with the upper right-hand match up in that group of four; is that correct?
Dr. BARGER - Would you repeat that again?
Mr. FITHIAN - In the vicnity of the red circle for shot No. 2---
Dr. BARGER - Yes. Mr. FITHIAN [continuing]. Two shots just below represent the same time frame.
Dr. BARGER - Exactly.
Mr. FITHIAN - You had to space it that way.
Dr. BARGER - That was artistic license; that is right.
Mr. FITHIAN - Now, if my eyes do not deceive me, the one immediately above that is also on exactly the same time frame, that 1.6.
Dr. BARGER - That is correct.
Mr. FITHIAN - The fourth shot up and to the right, does that not represent a different time frame?
Dr. BARGER - This is the fourth detection, not the fourth shot.
Mr. FITHIAN - I am sorry. The fourth detection.
Dr. BARGER - Of the four we have discussed so far. Yes. That one is this one. In other words, four of the matches in this segment of the tape which I have listed here as occurring at this time, were one, two, three, four, those all match at exactly the same place in the tape.
Mr. FITHIAN - And you eliminated the highest, the one clear up at the top next to the limousine, because that would make the motorcycle going 100 miles an hour?
Dr. BARGER - Yes. For a reason wholly unrelated to the evaluation of the test. I don't know whether there is another question remaining.
Mr. FITHIAN - I am wondering if any of the rest of those four down there are clearly false alarms.
Dr. BARGER - I don't have any good indication that any of them are.
Mr. FITHIAN - If I am not mistaken, the upper right-hand one of those four is beyond the 2-second time limit on your linear scale at the bottom; is that correct?
Dr. BARGER - That is correct. This particular match occurred at a different time than the other four. This one occurred at a slightly later time. It achieved a rather high value above the threshold of the cross-correlation coefficient, but it did it in a way that was unlike any of the other 14. The early echoes in that particular pattern didn't match with anything. It was all the later ones that matched. Therefore, the first match that was actually achieved in the echo pattern did not correspond with the leading edge of the echo pattern. In a sense, it is conceivable the leading that edge of the echo pattern could have been obliterated at that time by transmission from another motorcycle, or whatever. That would explain why its leading edge was off and its timing was bad. I included it in the results of the tests because objectively it had, in fact, exceeded the threshold of 0.6.
Mr. FITHIAN - Now, move to the third, which would be your green shot, or green match up. That is the one that is 5.9 seconds later, or whatever the time is Mr. Cornwell. Now, am I not correct in visualizing that all three of those match ups are exactly on the same time frame?
Dr. BARGER - That is correct. All three of those occur at the same time, 145.15 seconds after the microphone button is stuck.
Mr. FITHIAN - So am I correct in assuming that if we are to discard that shot altogether or that echo pattern altogether, we have to discard all three of those despite the fact that you have three match ups on exactly the same time frame?
Dr. BARGER - I am not sure I understood that.
Mr. FITHIAN - Vertically. In the third verticle.
Dr. BARGER. These three?
Mr. FITHIAN - Yes. Those matchups occur from some kind of an impulse that goes at exactly that time; is that correct?
Dr. BARGER -. That is correct.
Mr. FITHIAN - So if we are to return to the three-shot theory, which has been existing for 15 years, we must reject all three of those as being false alarms of some sort; is that correct?
Dr. BARGIN. No; that is not correct. Or if it is true, I don't know why.
Mr. FITHIAN - If there are only three shot impulses on that tape you got from the Dallas police force, and we all agree one of them is down in that blue circle and that caused all those matchups as No. 1, and we agree there are three matchups that are very close to the red circle for No. 2, that accounts for two shots.
Dr. BARGER - Yes.
Mr. FITHIAN - Then if we are going to accept the final series as the head shot--that is the one you have in black clear up the linear scale--if we are to reject an intervening shot, whatever the number is, we have to say that all of the matchups on that time line are false alarms.
Dr. BARGER - Yes, that is correct. If that were to be rejected for any reason, then all of those at that time would have been false alarms, that is correct.
Mr. FITHIAN - You said you didn't prove we had four shots and I was trying to eliminate one. There are four time line groupings that indicate four shots, so we have to do something to eliminate one of the sets of impulses which are line up on that vertical. Am I on the right line?
Dr. BARGER - If there were in fact three, it would be necessary to identify either this one or both of these, or four of these, or three of those as false alarms. There are other possibilties. Because of sound we have found no evidence of more than four, but we have found there may be four and if there are they occurred with this time sequence.
Mr. FITHIAN - Congressman Edgar calls my attention to the fact that in the third sequence, the one we just referred to now, the green sequence, that one of those is from a shot fired at target No. 2.
Dr. BARGER - Yes, that is correct.
Mr. FITHIAN - If we match up the Zapruder film, it seems rather unlikely since the limousine is on down the way a little further than that.
Dr. BARGER - The target location is one target location removed, but that is not a very large difference.
Mr. FITHIAN - I think that is all the questions I have on that particular chart. Did you and your team reconstruct for the committee the sound of the gun shots as they would have been heard if in fact we are to accept this final chart with four impulses? Do we have a sound recreation of that?
Dr. BARGER - Mr. Robinson has prepared a tape spliced up of the four test shots that were representative of the four possible locations where there might have been shots and I believe he is prepared to play that.
Mr. FITHIAN - If the Chair would permit, I would like to have it played.
Chairman STOKES. You may proceed.
Mr. CORNWELL - Mr. Chairman, we might identify it for the record as a tape recording, JFK exhibit F-353 and we would like to have it admitted into evidence.
Chairman STOKES. It will be so identified and so ordered. [Tape recording played for the committee.] [JFK exhibit F-353 is retained in committee files.]
Dr. BARGER - I think it would be appropriate for me to tell you where those sounds are recorded. That was microphone 5. If we can see the exhibit that has the map of Dealey Plaza----
Mr. FITHIAN - I believe it is JFK exhibit F-337. I have one last question on that anyway.
Dr. BARGER - What you just heard were the sounds picked up at this microphone of shots fired from here, the first two; one shot then fired from here, followed half a second later by one shot from there.
Mr. FITHIAN - Could you point to the place on the street where the motorcycle would have been located when the third of those impulses or shots were recorded?
Dr. BARGER - Yes. The estimate of the motorcycle position that we achieved by this test placed it 120 feet behind the Presidential limousine. Given that the Presidential limousine was just short of frame 313 at the time of the fourth shot, the position of the motorcycle was then 120 feet behind it at this position. In fact that green dot represented the estimated position of the motorcycle at the time of that third impulse that we detected that might be the knoll shot, in fact. The black dot here represents the position of the motorcycle where it would have been at the time of the fourth impulse that we identified as a possible shot.
Mr. FITHIAN - Thank you. I have one last question having to do with the authenticity of the tape itself that you worked with. I am sure that many will want to know whether or not there is internal evidence or otherwise that can attest to the fact that the tape which you were working with--that is, the original tape you were working with--was indeed a tape of the shootings in Dealey Plaza on November 22, 1963. What information can you shed as to your best judgment as to which tape you were working with?
Dr. BARGER - In the first place, the tapes that we received from the committee staff were represented as being that. However, at a different time we received a Dictabelt, which is a plastic continuous blue colored belt that was marked as "Being recorded from Channel 1" in a white marking pencil. Channel 1 of the Dallas police tape on November 22, 1963. We obtained a rebuilt Dictabelt recorder, newly rebuilt, and we played that Dictabelt and made our own magnetic recording of the Dictabelt. We then analyzed this middle segment around 12:30 of that recording that we had made from the Dictabelt on the same computer and in the same way that we had the first one and had it print out a record, a wave form record. We compared the two and found them to be identical in virtually every detail.
Mr. FITHIAN - And, the appearance of the Dictabelt, was there anything there that would indicate anything to you?
Dr. BARGER - It had the appearance of having been played a great deal and being quite old. The margins of the belt were cracked and it was necessary to tape them together to prevent further deterioration in the plane.
Mr. FITHIAN - Are you satisfied from ascientific analysis and in fact the way you have described it carefully this morning, that this particular recording passed all of your six screening tests; that you were indeed working with a recording of Dealey Plaza, November 22, 1963?
Dr. BARGER - Yes. The likelihood that the shape of the patterns that we achieved correlations on having come from some other place, seems extremely remote to us.
Mr. FITHIAN - I would ask staff counsel Cornwell whether or not we have additional information on the chain of custody.
Mr. CORNWELL - We do have additional information, Congressman. We had obtained the tape recording and Dictabelt originally from Mr. Paul McCaghren, who is now a retired member of the Dallas Police Department. We know the details of the story that we received at the time we got the tape from Mr. McCarran. He is here today. I can either summarize for you the information he has provided, or he is available and if the committee so desires, he could testify as to those facts himself, at your convenience.
Mr. FITHIAN - Mr. Chairman, I would not want to interrupt the committee's questioning of the witness now on the stand, but I would ask that immediately upon conclusion of this we bring the witness forward who can attest and I think probably very briefly, but certainly as to the chain of custody. I think it is very important that we do this.
Chairman STOKES. The Chair will be glad to entertain that.
Mr. FITHIAN - Mr. Barger, I certainly want to thank you for your answers and your insight and I would appreciatey our final collective judgment as to whether there are three or four impulses on that tape that could represent gunshots?
Dr. BARGER - We have endeavored, Mr. Fithian, to make as powerful a detection test as we could devise and to lower the acceptance threshold of those matches that passed the threshold so that all likely correct detections would emerge. In so doing, we found that the process had sufficient noise in it that some of the detections that passed our threshold are false alarms. We believe that the chances are very high that we have in fact located the motorcycle and, of course, that was done by matching sounds of gunfire. Therefore, to believe the probability that there were at least two shots is very high because it would take at least two to establish that pattern on the chart. You can't draw a straight line through one point. The indication is that there are probably somewhere between three, maybe six additional falsealarms that we cannot on our own information correctly identify as false alarms. There fore, we think each of the detections that we have made is about equally likely to be a false alarm. As there is only one detection remaining for the third shot--I don't remember what color it was, but it was the knoll shot, it is about equally likely that it is a false alarm. Therefore, it is about equally likely that there were three shots. However, there is an equal likelihood that there were four, and if there were, we have determined the time at which they occurred and, we also believe, the location from which they came.
Mr. FITHIAN - If there were four locations from which they had come, it would have been where?
Dr. BARGER - They would have been those indicated in the chart that was up there a little while ago. At the first time, all of the detections that were not Clearly false alarms were fired from the Book Depository. At the second time, 1.6 seconds later, likewise those that have not been identified as clearly false alarms are from the depository. At the third time, the one that is not disqualified by in appropriate motion of the motorcycle is from the knoll. At the last time, half a second later, those two nondisqualified detections are both from the Book Depository.
Mr. FITHIAN - Thank you. Thank you, Mr. Chairman.
Chairman STOKES - The time of the gentleman has expired. The committee will now proceed on the 5-minute rule. Doctor, I am going to ask that you replay the tape that you played a few moments ago. Prior to playing the tape, I am going to ask you to tell us what we ought to listen for and ask you further to tell us precisely what we should condude from what we have heard.
Dr. BARGER - I wouldn't presume, Chairman Stokes, to tell you what you should conclude from anything.
Chairman STOKES - What do you conclude from what you hear as an acoustical expert and as a scientist?
Dr. BARGER - You are asking me my opinion of the sound of those shots now before they are played a second time?
Chairman STOKES - Yes.
Dr. BARGER - I just heard them for the first time in that order. Of course. I heard them singly several Sundays ago in Dallas. I really think my opinion about them is of no particular value. Professor Green, who will follow me, is an expert on how sounds affect people. I am more expert in how sounds affect microphones. I must say, when I just heard them it sounded like test shots that I heard several Sundays ago. Why don't we hear them again?
Chairman STOKES - May we have the tape played again, please? [Tape replayed.]
Dr. BARGER - Let me add all of the hissing noise you hear is necessary to make the impulsive sounds sufficiently audible because they are so brief that they have to be loud in order to be clealy heard.
Chairman STOKES - Now, you are in a better position to respond to my original question.
Dr. BARGER - I understand the question is, what do I think those sound like, is that correct?
Chairman STOKES - In order to help me, when listen to that tape can I come to a conclusion from what I appear to be hearing?
Dr. BARGER - I think not. The microphone is a device that accepts sounds from all directions with equal facility, where as the human ear is not. The human can make a judgment about the directions from which the sounds arrive and this was not a stereo recording so we haven't been able to replicate the directionality of the sounds and echoes, and therefore I just don't believe I can reach a meaningful conclusion about how those sounds should be interpreted.
Chairman STOKES - I am rather concerned about the 9-foot uncertainty which you ascribe to the location of the motorcycle. I believe that is your testimony, is that right?
Dr. BARGER - That is correct.
Chairman STOKES - In order to reduce or lessen the uncertainty with reference to the placement of the motorcycles, can you tell me to what degree you have studied the Zapruder film or any other films or to what degree you have studied photographs in order to try and reduce the uncertainty?
Dr. BARGER - I think the only way that photographs would be helpful would be to show where the motorcycle in fact was. I know of no such photographs at the time of the shooting.
Chairman STOKES - What I have in mind, Doctor, is with reference to the placement of the motorcycle because that is where the uncertainty comes. That is precisely where the motorcycle was in Dealey Plaza at the time each of the shots were fired, is that correct, and that is where the uncertainty comes in?
Dr. BARGER - That is where some of the uncertainty comes from.
Chairman STOKES - You make an allowance of something like 9 feet in terms of the uncertainty, is that right?
Dr. BARGER - We made an allowance in the correlation procedure to accept some uncertainty in the microphone location.
Chairman STOKES - All I am attempting to ascertain from you is something to reduce or lessen that uncertainty as much as is scientifically possible. To what degree did you study any available photographs or films in order to try and make a more accurate placement of the motorcycle?
Dr. BARGER - Well, before we conducted the detection experiment, we had absolutely no idea which motorcycle it was. We could look at motorcycles a lot and it wouldn't tell us anything. After we did the detection experiment and then had the position of the motorcycle revealed to us, we found, in fact, that it appeared to be about 120 feet behind the limousine. We looked at the photographs available to us, to see if there were any photographs taken at the time of the shooting of that part of the motorcade about 120 feet back, and we found none. We have seen some photographs taken less than l minute before the shooting, and there are motorcycles back there, but there is so much time elapsed between those pictures and the time of the shooting, it wouldn't help us within 9 feet.
Chairman STOKES. My time has expired. The Chair recognizes the gentleman from Ohio, Mr. Devine.
Mr. DEVINE - Thank you, Mr. Chairman, and thank you, Doctor. I think you are a very patient man to go through all of this in the methodical detail as you have. I have a couple questions as a nonscience layman. I would like to know what is your definition of a false alarm.
Dr. BARGER - A false alarm is the correct description in detection theory for an indication from your test that an event occurred when in fact it did not occur. Our test, which was a correlation detection test was set up to give an indication that an event occurred whenever the correlation coefficient exceeded 0.6. Every time that happens there are two possible outcomes. One is, we have got the indication of the gunfire event when, in fact, there was a gunfire event at that time--let's call it a detection. The other possible outcome is there was not, in fact, a gun fire event at that time. That is called a false alarm. In other words, it is an error, a mistake.
Mr. DEVINE - Well, it either happened or it didn't happen, I suspect, when we are talking about either soundwaves or whatever detection you are talking about. I was under the impression it might be a convenient way to eliminate the unexplainable.
Dr. BARGER - Unfortunately, there is no way to eliminate the unexplainable that I can explain. False alarms don't have to be hard to find. Some of our identifications of false alarm are easy, in that they would require the motorcycle to fly all over the place. On the other hand, a false alarm can mimic a correct detection, and if it mimics it well, it is hard to identify as a false alarm. In fact, I present the results of our test in this way, with the hope that it will simplify the job, in the face of uncertainty, of the committee to consider other testimony that potentially verifies or refutes these findings.
Mr. DEVINE - I believe you said in your summary by your tests you have located at least two shots that were fired that were not false, and that there was an equal likelihood that there was a third or fourth shot. I mean it is likely that there was or wasn't a third and or fourth shot. Now, in listening to the recording which I have had an opportunity like all others here to have heard just twice it seemed to me as one who was in the past a firearms expert, having spent alot of time on the range and recognizing rifle fire, my personal interpretation based on that tape that I heard that the first, the second and the fourth noises sounded to me quite a bit like a rifle shot, the third noise that immediately preceded the fourth sounding like possibly something else. I am not that sure, and I haven't had enough time to listen and study, but it brings me back to what you said earlier--I think it was brought out in Mr. Fithian's questioning that Secretary Connally couldn't possibly have heard the shot that hit JFK's head before the sound of impact when the bullet hit the head. To the contrary, he may have heard the head explosion before he heard the shot that did it. Isn't that likely due to his immediate proximity to the President, and the distance from which the shot was fired, the muzzle velocity, and so forth. Isn't it possible that he could have heard that head explosion prior to the sound of the shot that caused it?
Dr. BARGER - If he heard the impact on the head, he would have had to hear it first.
Mr. DEVINE - I don't know if you were here when he testified. But, he startled the room by clapping his hands on the sound that he thought was the head hit.
Dr. BARGER - Yes.
Chairman STOKES. The time of the gentleman has expired. The gentleman from North Carolina, Mr. Preyer.
Mr. PREYER - Thank you, Mr. Chairman. Following up the comment of Mr. Devine about the sound of the shot hitting the President's head, that Mr. Fithian asked you about, one thing I would like to get the record clear on: I think you stated you had no opinion as to how a bullet would sound hitting the President's head, but can you say one way or the other that it would not be nearly as loud a sound as the sound of a rifle shot firing?
Dr. BARGER - I have here the sound of rifle shots. I haven't heard anything approximating that other event, and, therefore, what I am giving you is not an opinion based on scientific evidence; it is an off-the-wall guess. I would imagine that the sound of an impact of that sort would not be as loud as a rifle shot.
Mr. PREYER - What I am getting at is, the last two patterns on the tape, the possible third and fourth shots could not possibly be (1) the rifle firing, and (2) the head exploding.
Dr. BARGER - Those events did not occur in that order; that is correct.
Mr. PREYER - In other words, nothing on the tape could possibly be an indication of the head shot sound?
Dr. BARGER - You could not interpret those sounds in that way; that is correct.
Mr. PREYER - We might have some confusion on that. You mentioned at the end of your statement to Mr. Devine that the committee should view this as evidence, as I understood you to say, which potentially requires verification. Something to that effect. Earlier my notes indicated you said something like this, "Since there are false alarms we must examine the other evidence to see whether this corroborates it or not." My question is, did you regard the evidence of your experiments here as what we would call in the law corroborating evidence only or would you consider it as direct primary evidence? In other words, you seem to be saying that this is not like an Xray, exactly, where you can see it and know it as a physical reality and a fact. But, that this is subject to errors, and subject to false alarms and that it should be used to corroborate other evidence which should not be used in itself to prove the truth of the statement it makes.
Dr. BARGER - I am not certain of the question, but I think you are observing that I said that the potential of the evidence that we are presenting, the test results that we are presenting, is as a potential corroborating force toward other evidence. It is also, of course, and if I didn't say this, I should have, a potential discrediting force when compared to other evidence. Is that what I didn't say that you think I should have?
Mr. PREYER - Well, I guess I am asking you how far the acoustic science has developed and the strength of the evidence of your test. That is, is it like a fingerprint that if it says one thing we know it is true and we disbelieve any contradictory evidence or is it a state that is still partly art and part science and that we should treat its results cautiously.
Dr. BARGER - The results of the test that I presented are--I have presented as objectively as I can--I indicate that it seems quite important that we can identify here and I have some of these detections that we achieved we can properly identify them as false alarms. I believe that the remaining ten or so are each about equally likely to be false alarms in themselves and I am required to say that by the uncertainty in the results and I am not sure that I am answering any question any more, and would you kindly help me by reminding--
Mr. PREYER - I think you have been conscientiously objective in understating rather than overstating. To put it in laymen terms are you saying that it is about a 50-50 chance that there was a third and fourth shot?
Dr. BARGER - It comes down to that because the third shot indicated in green is supported by only one detection. Since I don't feel I can put more confidence in any single detection than I have indicated, the possibility of the third impulse pattern actually representing a shot is about even. Therefore, the question of four or three depends on that one detection. It comes down to what you said.
Chairman STOKES. The time of the gentleman has expired. The gentleman from Connecticut, Mr. Dodd.
Mr. DODD - I think you may have just answered my question, Doctor, in your answer to Judge Preyer's last question to you. But, for the purpose of clarity, you have obviously made a judgment here with regard to the probabilities of certain indications on the spectrograph being what would appear to be gunshots. Could you state for us what the probabilities are as for the first, second, third, and fourth sounds being gunshots?
Dr. BARGER - Yes, I will attempt that. Altogether I said the pattern of the detections that we achieved were tested statistically and found to be such that they would have arisen by chance only 5 percent of the time. So I think therefore the probability that we have found at least two is very high.
Mr. DODD - What would you mean by very high? What are you talking about?
Dr. BARGER - I think I just said I meant 95 percent. The necessity that others be accepted
Mr. DODD - Would you try to speak into the microphone, Doctor?
Dr. BARGER - The requirement that a third one be accepted would be dependent on either of two of the detections standing up in the fourth area or three standing up in the first area, for example. Those are reasonably likely in the first case, less so in the fourth case because it has only two. An estimate on my part to state the probabilities, which you have asked about--and this is hard to do because I don't want to confuse the results of the tests as they stand. The probability that there are two that we have detected is 95 percent. The probability there are three that we have detected correctly is probably somewhere between 60 or 70 percent; the probability that there are four is lower than that, around 50 percent.
Mr. DODD - Thank you. Could you indicate for me what effect the location of the targets has on the waveforms produced by rifle fire? Looking at JFK F-367, there are target locations that seem to change and I was trying to follow you as you were trying to identify false alarms and what you think may not be false alarms and correlating those to target locations. Is there a significant difference and, if so, in the third area--I guess that is green over there--could you indicate to me what the target location differences would mean there?
Dr. BARGER - I am not sure I understand that question.
Mr. DODD - Let me first of all ask you, does it make a difference?
Dr. BARGER - What target gave the correlation?
Mr. DODD - Target location.
Dr. BARGER - Yes.
Mr. DODD - How about the wave form produced by rifle fire?
Dr. BARGER - Yes. The exact location of the target has a different effect on the echo pattern depending on the location of the rifle, the target and the microphone. If the rifle is pointing approximately 90(deg )or so away from the direction between the rifle and the microphone, then the location of the target has very little effect because the shockwave radiated by the bullet which is dependent on which way the gun is firing, never reaches the microphone anyway. However, if the target is in such a location that the shot passes near to the microphone on its way to the target, then a change in the target location is important because in that case the sound of the shockwave is in fact a part of the pattern.
Mr. DODD - Looking at the 145.15 second block--that is the green block---
Dr. BARGER - That is correct. That is green.
Mr. DODD - We have got two separate target locations there. Do you have that before you? Can you see that? The first one as I can see it is the knoll; the second one is the School Book Depository, and the target location is 2. The third is Texas School Book Depository and that is in the first three, is that correct?
Dr. BARGER. That is correct.
Mr. DODD - Now, which of those did you exclude as a false alarm?
Dr. BARGER - The last two were excluded as a false alarm because they were detections made in microphones 7 and 8, which are about 60 feet away from microphone 4 where the other detection was made. It would have been necessary for the motorcycle to be speeding up in order to achieve that position in the time allowed and the sound of the motorcycle was in fact diminished all throughout that time.
Mr. DODD - I am sorry to ask you to repeat. If you accept the existence of a fourth shot occurring there in the black figures, then the third shot you would have to accept as the rightful location being on the grassy knoll?
Dr. BARGER - Well, under the presumption that you couldn't fire from the same place within a half second, that would be true. I think that is what you mean.
Mr. DODD - Thank you very much.
Chairman STOKES - The time of the gentleman has expired. The gentleman from Connecticut, Mr. McKinney
Mr. MCKINNEY - As I listen to your reenactment of the tape, there is a distinct difference between the third shot fired--not just a time difference, but a sound difference--between the third shot fired and the first, second and fourth. Is my impression correct?
Dr. BARGER - It does sound different to me, yes.
Mr. MCKINNEY - It does sound differently to you?
Dr. BARGER - Yes.
Mr. MCKINNEY - Since that shot sounds differently and also is much closer to any other shot in time--at least from the reenactment--how can you be sure that particular shot is not a false alarm? In other words, you have two shots, at least to my ear--and I know my ear is not very accurate--that sounded alike in the beginning and then you have a third shot followed almost immediately by another one in the reenactment. The third shot sounds quite differently. What is it about that particular shot that had you include it, in other words might have told you that it wasn't a false alarm or something else?
Dr. BARGER - Nothing has told me it is not a false alarm. The features of that shot that caused it to have been detected in the first place was simply that the pattern generated by it at that microphone matched sufficiently well with the noise on the tape at that time that it was accepted as a possible detection. I don't know whether it is a false alarm or not.
Mr. MCKINNEY - So then could I assume that the likelihood that if any of the four shots that we heard were false alarms, that you could presume more strongly that it is third one?
Dr. BARGER - I think you are looking for an indication of the power of the test to find a shot, given that one may be quite different than another, and would the different one be easier to find. Is that the question, or am I completely off?
Mr. MCKINNEY - I guess what I am really saying is that we seem to have three occurrences that are pretty similar--one, two and four.
Dr. BARGER - Yes.
Mr. MCKINNEY - And we have a third that looks differently, and sounds differently. I was just questioning as to whether or not that was the one that you could presume was most likely to have perhaps been something else, or perhaps been another occurrence, or backfire, or something.
Dr. BARGER - I don't have the information to answer that. I don't know about other occurrences.
Mr. MCKINNEY - Neither do I.
Dr. BARGER - But I do know about test shots fired in Dallas. All I can say is that particular sound on the tape sounded sufficiently like one of the test shots in Dallas to have scored above the threshold.
Mr. MCKINNEY - But then if we were to accept that third shot as we heard it in the reproduction as a shot, it would have had to have come from the grassy knoll?
Dr. BARGER - That is correct. If it occurred, that is where it came from.
Mr. MCKINNEY - Not to get back into the game of probabilities, which we already played down the line, would you consider--is your probability on the third shot the lowest of the group?
Dr. BARGER - Yes.
Mr. MCKINNEY - Thank you very much.
Chairman STOKES. The time of the gentleman has expired. The gentleman from Tennessee, Mr. Ford
Mr. FORD - Thank you, Mr. Chairman. Mr. Chairman, let me ask a question to you and to the staff at this point. Dr. Barger mentioned earlier, when you questioned him, that they conducted an analysis of the police tape, and the tape that was done in Dallas with the experiment. Just which tape did we hear a few minutes ago?
Dr. BARGER - Was that my question?
Mr. FORD - I was asking--maybe the staff. Yes, I will raise the question to you.
Dr. BARGER - What you were hearing were the sounds of four of the test shots recorded in Dallas 3 weeks ago, or whenever.
Mr. FORD - The tape that we heard a few minutes ago---
Dr. BARGER - Yes, was prepared by splicing together four of the shots that were recorded during the reconstruction.
Mr. FORD - So we are not talking about the tape from the police motorcycle.
Dr. BARGER - Well, we were not listening to it; that is correct.
Mr. FORD - I was under the impression that we were listening to the tape from the police motorcycle of 1963, but we were not.
Dr. BARGER - No, sir. If it had been that distinct, we would have followed an entirely different detection scheme that would have been much easier to explain.
Mr. FORD - Let me ask you another question. From what you said earlier, are you able to distinguish from which directions the shots came? I recall your earlier testimony regarding three shots and a possible fourth shot, and different directions. Are you able to pinpoint that and, at the same time, unable to determine if there were three or four shots fired?
Dr. BARGER - Well, we can only imply the direction of the shot by the location of the target and the gun for the test shot that matched. In other words, each time we get a match between the noises, the impulsive noises on the Dallas police tape made during the assassination, and each time one of those noises correlates or matches with one of the echo patterns, we can only infer what the direction of the shot was by knowing what it was during that test shot. Otherwise--that is the procedure.
Mr. FORD - All right. I was reading here that the team of scientists headed by you concluded that a reliable and credible conclusion could be determined if they could test and analyze in three crucial areas. When you appeared before this committee, however, you testified that you could not be sure whether there were three or four shots fired on November 22, 1963. So, we are not able to pinpoint that at this time; is that correct?
Dr. BARGER - The results of the tests are inconclusive to the degree that I described them, I believe, when I was answering Mr. Dodd's question, or Congressman Preyer--I am not sure whose question it was. There is uncertainty in the results, as I described it.
Mr. FORD - I don't have any further questions, Mr. Chairman.
Chairman STOKES - The time of the gentleman has expired. The gentleman from Pennsylvania, Mr. Edgar
Mr. EDGER. - Thank you, Mr. Chairman. Mr. Chairman, I have to admit that I am a little bit confused, and I would like to try to clarify some of what I have heard throughout today. Your testimony has been detailed. Let me just ask you this question. Before you went to Dallas, before you went to Dallas to do the experimental test, you were more sure, I believe, of four impulses which you found on the original tape. That was one of the reasons why you came back to the committee to suggest that the test firings be held. It seems to me that after the Dallas trip you seemed less certain of the four-shot indications that you received though the computerized acoustics. Why is that?
Dr. BARGER - Because the tests that I had performed at the time that I spoke to the committee previously were the screening tests that I described today. These are very weak tests. It is not particularly difficult to pass them. You recall they had to occur at the right time of day, they had to have the total timespan of 5 seconds or more, they had to have the right kind of distorted waveforms. There were six in total. These were not very stringent tests. There were, in fact, four patterns, or four segments of the tape that had impulses on them that passed these weak, nonstringent tests. The opinion that I intended to convey at that time was that I could not rule out that the impulsive events in these segments of the tape were in fact gunfire because they had passed those six screening tests. On the other hand, I said there was no way I could be sure that they were because the data were so noisy and that there was no way I could be sure, unless I could find out what echo patterns were in fact generated by gunfire in Dallas. I described that as a test that was the best one that we could conceive to determine whether those impulse patterns were in fact shots or not. Mr. EDGER. As I remember it, you had a long roll of paper that you rolled out across the table for us.
Dr. BARGER - Yes.
Mr. EDGAR - And you were able to indicate four patterns of blips on your computerized paper that indicated something occurred in those four time frames.
Dr. BARGER - Yes.
Mr. EDGAR - Do the four timeframes that are on the weak evidence-that is, the pre-Dallas evidence--correspond to the timing, the minutes and seconds timing, that is listed alongside the four possible shots that you indicate in today's testimony?
Dr. BARGER - No. Of the four impulse patterns that I had originally described, the first three proved to give us detections in this matching test that we performed. The fourth did not. However, we got two in the third that I showed you that time. In other words, my indication of the general areas that might contain matches with gunfire sounds were approximately correct, but not in detail.
Mr. EDGAR - Approximately correct, but not in detail. Was there one of those weak impulse areas that, after going to Dallas, you can discount as being a gunshot?
Dr. BARGER - Well, yes, I think I understand that question. I showed four segments of the tape that had patterns that I thought might be gunfire, because they passed these six screening tests, and the last of those four did not subsequently prove to contain any.
Mr. EDGAR - So that it was the third tentative weak gunshot that has now been divided into two possible gunshots?
Dr. BARGER - That is correct.
Mr. EDGAR - And you say it is a 50-50 chance that the fourth gunshot described up here is just a 50-50 chance; is that correct?
Dr. BARGER - That is correct. I have insufficient evidence to state anything stronger or weaker than that.
Mr. EDGAR - Is there any test that we could make that could reduce the uncertainty?
Dr. BARGER - Congressman, the answer to that literally is yes. Now that the position of the motorcycle has been fixed with some confidence one would not bother with microphones all over other parts of Dealey Plaza, for example. However, I believe that the advantages to be gained from rectifying that problem are very marginal, and I doubt if they could reasonably be expected to improve the level of uncertainty in the test.
Mr. EDGAR - When I go home to explain what I have heard today to my 11-year-old son, who is in the seventh grade, what do I tell him?
Dr. BARGER - How much time do you have? [Laughter.]
Mr. EDGAR - I have all of the evening dinner to explain to him what I heard. I am just trying to get it into a language that I can communicate with him.
Dr. BARGER - That is a good question. I think the answer would go something like this. There was, by a considerable measure of chance, a motorcycle in the motorcade with its radio in an operating condition, but with the motorcycle policeman not speaking into it. The motorcycle was just moving. Over that radio were heard a series of sounds, including the motorcycle, including other radios, and including the possibility of the sounds of the assassination of the President. What you were observing today was the description of a test that was made on that tape to see if it was statistically likely to have contained the sounds of gunfire. You found out that it was possible from this test to locate the position of the motorcycle with a good deal of confidence 15 years later. It turned out that the motorcycle was about 10 feet short of the corner, at the approximate time of the first gunfire, when the motorcycle noise in fact was observed then to abate, and the man slowed down. You found also that motorcycle was in a position, found to be in a position, when the first shot was heard, that corresponded to the limousine being in the position where it was at approximately the time of the first shot. For these reasons and others that I have described, there is good confidence that the motorcycle has been found. Therefore, good confidence that some of the shots have been correctly detected. There is less confidence in questions of increasing detail, and I hope he enjoys the story. [Laughter.]
Chairman STOKES. The time of the gentleman has expired.
Mr. EDGAR - Thank you.
Chairman STOKES. The gentleman from Michigan, Mr. Sawyer
Mr. SAWYER. - I have been following the testimony reasonably closely, but I am somewhat perplexed. You actually caused these shots to be fired in the same environment as the other shots were fired, with the same echoes and refractions and reflections and whatnot. So, you have a known-namely, your own--recording of what you knew were shots. Now, were you able then, by comparing that to your oscillographic pictures of what was on that tape, to say what was on that tape were or were not shots?
Dr. BARGER - Was able to--
Mr. SAWYER [continuing]. Determine whether what was on that motorcycle tape originally were or were not shots, these disturbances?
Dr. BARGER - We were able to determine that with considerable uncertainty that I have described.
Mr. SAWYER - You were not, then, able to determine at least to the point of forming a scientific opinion that those were shots?
Dr. BARGER - It is my judgment, our judgment, the judgment of the team that did this study, that we have detected with about 95 percent likelihood, at least two of them, and on down the scale that I described for Congressman Dodd or Preyer--I still can't remember which.
Mr. SAWYER - You have described now a number of times these probabilities. But let me ask you this. I am not an expert, and no one else on this panel to my knowledge is, certainly in this type of thing. You have had a chance now to conduct the test, to examine the tape, to examine the results. Do you have an opinion yourself, aside from any other evidence, based just on your tests of this tape, do you have an opinion as to whether there were three or four shots fired?
Dr. BARGER - I have gone to some pains to present my opinion. I believe that I have presented the results of this test as clearly as I know how.
Mr. SAWYER.- I understand all that, but now you have explained the pros and cons of the test. But laying aside any other evidence, you have now conducted the tests, and you have looked at the oscillograph of this motorcycle tape. Now, do you as a professional in this area have an opinion as to whether or not there were three or four shots fired?
Dr. BARGER - Congressman, I can't add any information by saying I think there are three or four. I believe the results of the test do not allow me to state with greater certainty than I have, the answer to that question.
Mr. SAWYER. Well, then all I can say is I would hate to civilly sue anybody, let alone prosecute anybody, on this kind of evidence. Thank you, Mr. Chairman.
Chairman STOKES - The time of the gentleman has expired. Doctor, let me go back for a moment and try and clarify something. It appears to me that in answering both Mr. Dodd and Mr. Sawyer, when you make reference to the probabilities, that you group the four shots in terms of the probabilities. When you say that two of the shots, the probabilities are 95 percent; three, the probability is 60 to 70 percent; and that the fourth is approximately 50 percent. Would you please individualize for us, and tell us which are the two where the probabilities are 95 percent, which is the one which is approximately 60 to 70 percent, and which is the one that is 50 percent.
Dr. BARGER - Congressman Sawyer isn't going to like this answer, but the probabilities that I gave you are based on not distinguishing which three, which two. In other words, the high confidence that we have is based on the high degree of order in the detections, and that can be established by two, any two.
Mr. SAWYER - Let me say I anticipated the answer, Mr. Chairman.
Dr. BARGER - If I might indicate possible mitigating circumstances for Congressman Sawyer, I do believe that even with this level of uncertainty, it is quite important to know when they occurred, if they did. I can see that Congressman Sawyer is not convinced of that.
Chairman STOKES - Let me ask you this. I would assume, then, from your former answer, that you are unable to identify what shot or impulses represented the grassy knoll shot or impulse?
Dr. BARGER - I think not. I don't believe that is a correct interpretation of the results. If the shot at that time, 7 1/2 seconds, indicated in green, stands up, then it was from the grassy knoll--it would not have been from the Depository.
Chairman STOKES - Now, I understand from your previous testimony that the shot which you simulated in Dealey Plaza from the grassy knoll was with a .32 revolver, or a .38?
Dr. BARGER - Well, the one with a pistol, yes. There was also a rifle fired from there.
Chairman STOKES - Simultaneously, or separately?
Dr. BARGER - No, separately. The tests included separate and distinct shots from rifles and from pistols, from the knoll.
Chairman STOKES - Well, with reference to the pistol, what caliber was that?
Dr. BARGER - 38.
Chairman STOKES - 38. And that is a subsonic or supersonic type of sound that emanates?
Dr. BARGER - The particular charge in the bullet used made it a subsonic projectile.
Chairman STOKES - The composition of the bullet gave you a supersonic result.
Dr. BARGER - I am sorry. Yes, we were firing a subsonic projectile from that pistol.
Chairman STOKES - All right. Now, is there a different type of acoustical representation that you will get depending upon whether it is subsonic or supersonic?
Dr. BARGER - Yes, there is. That is why we also fired a rifle from the knoll because it has a supersonic projectile.
Chairman STOKES - I see. So that in terms of the simulation, and in the absence of any real knowledge as to whether a subsonic or supersonic type of firing came from the grassy knoll, you are unable, with any real degree of certainty, of being able to say that is in effect a real simulation, aren't you?
Dr. BARGER - If that one should stand up, that shot from the knoll matched with a rifle shot, and not a pistol shot. The match achieved with the pistol shot was very poor. Therefore, it is possible with confidence to distinguish on that point, and it would appear that there was not a subsonic projectile fired from the knoll.
Chairman STOKES - I just have one further question. With reference to attempting to simulate the scene as you did, to what degree did the lack of a crowd such as there existed on that particular day in 1963 affect your simulation?
Dr. BARGER - Well, it affected it very little because the sounds that are scattered from a person are of the sort that I described earlier today, as scattered sounds. This is the weakest form of redirecting the sound from a source and into a receiver. Our thresholding procedure, which eliminated all of the weak sounds, both in the test pattern and in the police tape, was designed to eliminate the contribution of weak echoes such as those due to the presence of people.
Chairman STOKES - I see. My time has expired. Other members seeking recognition? The Chair recognizes counsel, Gary Cornwell.
Mr. CORNWELL - We have to leave you in a few moments, I am sure, Dr. Barger. We want to take away from your presentation whatever we can of a constructive nature. You made a statement informally to me last evening which I think you mentioned previously in your testimony, but nevertheless, it might merit further explanation for just a moment. That, as I recall, was to the effect that a scientist such as yourself can basically give us the data, and can to a limited degree provide us some insights about the probabilities of any one aspect of the data occurring by random chance, but that once you present us with the data, it is the committee's problem then to decide how to interpret it in the end. Is that correct?
Dr. BARGER - That is correct.
Mr. CORNWELL - From your point of view, then, all you can do to help us unscramble the chart is to tell us what a mechanical, numerical calculation of some type, how it comes out, with respect to the random chances of various events occurring. I take it there is no probability which will tell us how many shots occurred, or which were the real ones and the wrong ones in the end. Is that correct?
Dr. BARGER - None that I know of beyond what I have mentioned.
Mr. CORNWELL - All right. So what we must do, then, is take the data and see what external corroboration or impeachment can be applied to it.
Dr. BARGER - That is my view, yes.
Mr. CORNWELL - Just so that we understand what help you can provide us in that task, I would like very quickly to run through the chart and use it with some hypotheticals out of it. Let's talk about the top line of each of the four time segments. In the first time segment, the top line is in microphone array 2-5, a shot from a TSBD, down toward target 1. The second shot, the motorcycle's apparent location is moved from mike 2-5 to 2-6, slightly up the street, another shot from the TSBD, down to the street and the target, somewhere in the motorcade. The next one, picked up with the microphone again slightly further down the street, a shot from the knoll, out to the motorcade. Finally, another shot from the TSBD, motorcycle again slightly further down the street, pointed at the motorcade. With respect to each of those four possible shots, apart from any probabilities, independently, we might say, they each occurred at the right time of the day, they each were unique in the data overall that you analyzed, they each occurred within a time span which did encompass at least 5 seconds, the shape of each of the impulses was what you would expect, the amplitude was roughly what you would expect, and the number of impulses or echo patterns in each were what you would expect from the geography of Dealey Plaza, is that correct?
Dr. BARGER - That is correct.
Mr. CORNWELL. - With respect to each one, the strict probability that that one would have occurred on that tape through some random sound source would be identical, individually viewed; that is .08, .08, .08, and .08. Correct?
Dr. BARGER - Well, the correlation coefficients were all .08, that is a fact.
Mr. CORNWELL - The tape on which each of them appeared is, to the best of your knowledge, a genuine tape made in Dealey Plaza on November 22, or from transmissions from there on that date?
Dr. BARGER - That is correct.
Mr. CORNWELL - Each of those four items appear very close, near to the line which you would expect the motorcycle to be traveling; in other words, the rate that it would travel down the street in the procession at approximately 11 miles per hour.
Dr. BARGER - That is correct.
Mr. CORNWELL - And independently we do know that there were shots fired in Dealey Plaza on the day at about the time that these impulses occurred on your tape.
Dr. BARGER - Correct.
Mr. CORNWELL - Then it would be the committee's job to apply independent evidence for each of those as an equal chance of being a genuine shot, to determine if it is genuine or if it is not.
Dr. BARGER - That is correct.
Mr. CORNWELL - I have no further questions. Thank you
Chairman STOKES. Thank you, counsel. The gentleman from Indiana, Mr. Fithian.
Mr. FITHIAN - One question, Mr. Chairman. Can we say that the shots, as far as time sequence is concerned, that were fired in Dealey Plaza at any time during that stuck microphone, any time during that time frame, had to have occurred at the following relative sequence: The first shot as zero, the second 1.6 seconds later, the third 5.9 seconds later, or at about 7.5 seconds after the zero time frame, and the fourth .05 seconds later, or at just shy of 8 seconds in the time frame?
Dr. BARGER - That is correct.
Mr. FITHIAN - There is no other acoustical disturbance of the tape that could possibly be a gunshot?
Dr. BARGER - We believe that the threshold that we set was low enough to accept all actual occurrences, and there were none other than those you just described, that is correct.
Mr. FITHIAN - - If, therefore, there were any shot that did not match this time sequence--well, to put it the other way around, there could not have been definitively, could not have been a shot in this time frame that did not match one of those four interruptions?
Dr. BARGER - That is correct.
Mr. FITHIAN - Thank you.
Chairman STOKES - Dr. Barger, at the conclusion of any witness' testimony before this committee he is entitled to a period of 5 minutes under our rules in which to explain or amplify, any way expand upon his testimony. I would like on behalf of our committee to extend 5 minutes to you at this time.
Dr. BARGER - Chairman Stokes, I thank you for that. I suspect that everyone has heard quite enough of me today, and I will respectfully decline to speak at any greater length.
Chairman STOKES.-You have had quite a lengthy day here with us. It has indeed been a real experience for us, in not only working with you today, but previous occasions we have had to be with you, and to discuss the matter which we assigned to you for your investigation and analysis. It has indeed been a pleasure to work with you and to have had the benefit of your testimony here today. On behalf of the committee, we thank you for having appeared here with us. You are excused, sir.
Dr. BARGER - Thank you, sir