| Test | Beginning Time of | Zap. | Zap. | Microphone Array | Rifle | Target | Correlation | Strong | Fluke |
| ID | First impulse on | Frame | Frame | and | Location | Location | Coefficient** | ||
| Tape Segments (sec) | BBN | Thomas | (Channel Numbers) | ||||||
| A | 136.20 | No Correlations Higher Than | 0.5 | ||||||
| B | 137.70 | 168 | 176 | 2 ( 5 ) | TSBD* | 1 | 0.8 | Strong | |
| C | 137.70 | 168 | 176 | 2 ( 5 ) | TSBD* | 3 | 0.7 | Fluke | |
| D | 137.70 | 168 | 176 | 2 ( 6 ) | TSBD | 3 | 0.8 | Strong | Fluke |
| E | 137.70 | 168 | 176 | 2 ( 6 ) | KNOLL | 4 | 0.7 | Fluke | |
| G | 139.27 | 196 | 205 | 2 ( 6 ) | TSBD* | 3 | 0.8 | Strong | |
| H | 139.27 | 196 | 205 | 2 ( 6 ) | TSBD | 3 | 0.6 | ||
| I | 139.27 | 196 | 205 | 2 ( 10 ) | TSBD | 3 | 0.6 | Fluke | |
| J | 139.27 | 196 | 205 | 3 ( 5 ) | KNOLL | 3 | 0.6 | Fluke | |
| K | 140.32 | 216 | 224 | 2 ( 11 ) | TSBD* | 3 | 0.6 | ||
| L | 145.15 | 304 | 313 | 3 ( 4 ) | KNOLL | 3 | 0.8 | Strong | |
| M | 145.15 | 304 | 313 | 3 ( 7 ) | TSBD* | 2 | 0.7 | Fluke | |
| N | 145.15 | 304 | 313 | 3 ( 8 ) | TSBD | 3 | 0.7 | Fluke | |
| O | 145.61 | 313 | 321 | 3 ( 5 ) | TSBD | 3 | 0.8 | Strong | Fluke |
| P | 145.61 | 313 | 321 | 3 ( 6 ) | TSBD | 4 | 0.8 | Strong | |
| Q | 145.61 | 313 | 321 | 3 ( 8 ) | TSBD* | 2 | 0.7 | Fluke | |
| R | 146.30 | No Correlations Higher Than | 0.5 |
ELLIOTT: HSCA 1978 Acoustic Study by BBN – Figure 367.
ELLIOTT: Bolt, Beranek and Newman (BBN) found two cluster of N-waves. Separated by about a minute. They focused on the first cluster. . . .
ELLIOTT: “N-waves” are found throughout the recording. And there are at least two cluster of “N-waves”, which are separated from each other by a minute. And a few other “N-waves” to be found here or there in the 5-minute recording. Since all the shots occurred within a 10 second period, it is impossible for all these “N-waves” to have been gunshots. So, it is clear that “N-waves” can be created by some other means then gunshots. Perhaps all of them were created by some other means.
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 shock wave 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 shock wave has an intensity of 130 decibels.
The muzzle blast 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 shock wave. It has a very sharp peak, a negative undershoot followed by quiescence, and these are characteristic of the waveforms of that rifle.(2 HSCA 23)
BBN did not conclude that there were gunshots recorded on the Dictabelt recording because “sound impulses” or “N-waves” were found on it.
In addition, Barger emphasized, the first part of the sequence of impulses identified as a shot from the grassy knoll was marked by an N-wave, a characteristic impulse caused by a supersonic bullet.(61) The N-wave, also referred to as a supersonic shock wave, travels faster than the noise of the muzzle blast of a gun and therefore arrives at a listening device such as a microphone ahead of the noise of a muzzle blast. The presence of the N-wave was, therefore, a significant additional indication that the third impulse on the police dispatch tape represented gunfire, and, in particular, a supersonic bullet.(62) The weapon may well have been a rifle, since most pistols except for some such as a .44 magnum--fire subsonic bullets.
The N-wave was further substantiation for a finding that the third impulse represented a shot fired in the direction of the President. Had the gun been discharged when aimed straight up or down, or away from the motorcade, no N-wave would have appeared.(63) Of the impulse patterns on the dispatch tape that indicated shots from the book depository, those that would be expected to contain an N-wave, given the location of the vehicle's microphone, did so, further corroborating the conclusion that these impulses did represent supersonic bullets.(64) (HSCA Report, pp. 74-75)
Mr. Elliott's post is a comedy of errors. Folks, if you read Mr. Elliott's replies about the acoustical evidence in the "Poor Scholarship on Display" thread and in his own "Question about Dr. Donald Thomas’s Dictabelt Offset Hypothesis" thread, you will see that he has horrendously blundered over and over again when it comes to the acoustical evidence
Let's start with Elliott's opening statement:
There is no Figure 367 in the BBN acoustical study. Somehow, Elliott misread BBN scientist James Barger's HSCA testimony as being the "HSCA 1978 Acoustic Study by BBN." The BBN acoustical study is in volume 8 of the HSCA volumes. Barger's testimony is in volume 2. Barger's testimony is where we find Figure 367. And anyone who reads Barger's testimony will quickly see that Elliott has grossly misrepresented, or misunderstood, the content and meaning of Figure 367.
Now let us address the heart of Mr. Elliott's post:
No, they did not find two clusters of N-waves. Such a claim shows a lack of understanding of even the basics of the BBN and WA acoustical research for the HSCA.
The "separated by about a minute" comment is based on Mr. Elliott's debunked claim that the Decker "hold everything" crosstalk is a valid time indicator and thus proves that the dictabelt gunshot impulse patterns were recorded 60 seconds after the assassination.
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 - 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.
No, N-waves are not found "throughout the recording." This is a comical, embarrassing error. Elliott either does not understand, or is hoping we do not understand, that there is a huge difference between N-waves and non-gunfire sounds that can look like N-waves when they are graphically illustrated on an oscillogram.
An actual N-wave, also known as a shock wave, is produced by a bullet traveling at supersonic speed. When a bullet is fired from a rifle, the N-wave will be recorded 15-30 milliseconds before the muzzle blast will be recorded, depending on the rifle's muzzle velocity and the ambient conditions when the N-wave was recorded. The muzzle blast, in turn, will be followed by the echoes of the muzzle blast. Also, the muzzle blast will be louder than the N-wave, so any N-wave graphed on an oscillogram will be followed by/come before a waveform with a higher/larger loudness peak, as Dr. Barger explained:
I have been asking Mr. Elliott for weeks now to address the powerful, intricate correlations between the gunshot impulse patterns on the dictabelt and the gunshots from the Dealey Plaza test firing. The following articles give a good overview of these correlations:
https://www.maryferrell.org/pages/Essay_-_Acoustics_Overview_and_History_-_part_2.html
https://www.maryferrell.org/pages/Essay_-_Acoustics_Overview_and_History_-_part_3.html
https://the-puzzle-palace.com/rebuttal.htm
And here is a helpful video by Dr. Donald Thomas:
https://aarclibrary.org/dr-donald-b-thomas-jfk-acoustical-evidence-challenge-and-corroboration/
Quote from: Michael T. Griffith
No, they did not find two clusters of N-waves. Such a claim shows a lack of understanding of even the basics of the BBN and WA acoustical research for the HSCA.
The "separated by about a minute" comment is based on Mr. Elliott's debunked claim that the Decker "hold everything" crosstalk is a valid time indicator and thus proves that the dictabelt gunshot impulse patterns were recorded 60 seconds after the assassination.
Quote from: Joe Elliott
No. My statement about other N-waves is not based on the “hold everything” crosstalk. It is Mr. Griffith who is misinformed. It is based on the statement made by Dr. Barger to the HSCA:
Quote
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.
Quote from: Joe Elliott
So, there are at least two clusters of “impulse patterns”, events with multiple “impulses” or N-waves. Both were similar, except the first one spanned at time of 10.1 seconds and contained 7 impulses. The second cluster was a minute later, contained an unspecified number of impulses, and covered less than 5 seconds. No where does he state that this second set of impulses were in any way fundamentally different from the first set of impulses. Instead, he was able to judge that this second set of “impulse patterns” was not of interest only because it spanned less than 5 seconds, too short to be all the gunshots.
If my claim is a ‘lie’, that there are other unexplained “impulse patterns” found on the Dictabelt that were not gunshots, I am not the original liar. The ‘lie’ originated with Mr. Griffith’s hero, Dr. Barger. Don’t blame me if you think this is a lie. Go blame Dr. Barger.
Quote from: Joe Elliott
From what I have read elsewhere, there are other isolated N-waves scattered here and there on the Dictabelt, basically sounding like static. In the 5-minute section of interest, there were these two clusters of N-waves, separated by a minute. They can’t all be gunshots because no one believes the shooting occurred over a span of a minute. Some of these N-waves must be non-gunshots. And perhaps, all of them are non-gunshots.
Quote from: Joe Elliott
I believe that there were other N-waves, in the 5-minute period, despite Dr. Barger’ statement: "We found no other impulsive patterns on the tape." [SNIP OF REPEAT OF BARGER QUOTE]
I believe he means no other “cluster” of impulse patterns, and was not referring to no other similar isolated impulses during the 5-minute period. If that is not what he meant, well, that would contradict what I have read elsewhere, that there are other isolated N-waves scattered over the 5-minute period in question, while the transmit key was stuck.
Quote from: Joe Elliott
Who knows how many such clusters would be found on the Dictabelt recording if the whole thing was every carefully checked for such clusters, and not just that 5-minute segment?
Quote from: Joe Elliott
Even of the 7 N-waves of the cluster the BBN looked at, the BBN concluded that 3 of them were probably not formed by gunshots, because they could not match them up with their firing tests which took place at Dealey Plaza. Later, Dr. Thomas claimed one of these rejected N-waves was a real gunshot. You claim the BBN rejected this as a shot solely because Robert Blakey would not accept more than 4 shots. But in actual truth, the BBN found that there was a weak correlation coefficient of 0.6 for the shot at z224 (Dr. Thomas’s estimate). All the other 4 “shots” that they did accept, had a correlation coefficient of 0.8, which is still not very strong, but at least better than 0.6. All this is to be found in Figure 337, provided by Dr. Barger, which is quite helpful in evaluating which of these alleged shots have the most support.
Quote from: Joe Elliott
Now, it may be that the three “Rejected” N-waves really were gunshots, fired from locations that the BBN did not test, because, of course, it was impossible to run tests firing rifles from every possible firing position. But the point is, that even Dr. Barger accepted that some of these “Sound Impulses” might not have been formed from gunfire. And probably were not. As opposed to Mr. Griffith who believes that all such “Sound Impulses” can only be caused by a gunshot and that there is no other possible explanation.
So, even the BBN concluded that many of the N-wave patterns, even some of those found in the 10.1 second cluster, were not caused by gunshots.
Quote from: Michael T. Griffith on Today at 01:14:07 PM
No, N-waves are not found "throughout the recording." This is a comical, embarrassing error. Elliott either does not understand, or is hoping we do not understand, that there is a huge difference between N-waves and non-gunfire sounds that can look like N-waves when they are graphically illustrated on an oscillogram.
Quote from: Joe Elliott
Wrong, see above.
Quote from: Joe Elliott
While Dr. Barger did not comment on this, I do remember reading that similar noises, which sound like static, are to be found throughout the recording. And we know of two such clusters, covering 5 to 10 seconds.
Quote from: Michael T. Griffith on Today at 01:14:07 PM
An actual N-wave, also known as a shock wave, is produced by a bullet traveling at supersonic speed. When a bullet is fired from a rifle, the N-wave will be recorded 15-30 milliseconds before the muzzle blast will be recorded, depending on the rifle's muzzle velocity and the ambient conditions when the N-wave was recorded. The muzzle blast, in turn, will be followed by the echoes of the muzzle blast. Also, the muzzle blast will be louder than the N-wave, so any N-wave graphed on an oscillogram will be followed by/come before a waveform with a higher/larger loudness peak, as Dr. Barger explained:
Quote from: Joe Elliott
Wrong.
The waveforms shown in this figure were produced by a Mannlicher-Carcano with Western Cartridge Co . ammunition and picked up by a microphone positioned 30 ft from the muzzle and 10 ft to one side of the bullet's trajectory. The muzzle blast waveform reveals a peak pressure impulse having a sound pressure level of 137 dB re 2x10 -SN/m 2. For comparison, Fig. 3 also shows the corresponding waveforms for an M-1 rifle.
Despite the differences in loudness (amplitude) from one weapon to the other, the shock wave and the muzzle blast can be seen to have characteristic shapes . Sounds processed from the Channel 1 tape could be expected to contain these shapes, but in distorted fashion. The shapes could be expected to be compressed in amplitude and to be accompanied by . indications of overdriving of the radio circuits. They would also be accompanied by waveforms produced by the arrival of sound echoes from several sources, as described in the rest of this section. (2 HSCA 16)
Quote from: Joe Elliott
Dr. Barger himself there were similar impulses a minute after the “gunshot” cluster.
Quote from: Joe Elliott
But rejected as gunshots because it spanned less than 5 seconds. He made no statement that the nature of these impulses was in any way fundamentally different from the impulses in the 10.1 second section they did study carefully. It was just that this second cluster lasted under 5 seconds, while the first cluster lasted 10.1 seconds. And it was for that reason they focused on the first cluster.
Because the five screening tests described in Sec. 4 had failed to disprove the possibility of gunfire having been recorded on the Channel 1 tape, a more rigorous test was required. The objective of the acoustical reconstruction, therefore, was to obtain several "acoustical fingerprints" of the sound of gunfire in Dealey Plaza to compare with the impulse patterns found on the Channel 1 tape. If any of the "fingerprints" matched, then the reconstruction would result in determining both the timing of the shots and the locations of the weapon and the target for each shot. (2 HSCA 80)
Quote from: Joe Elliott
The correlation of the shots in time with their position in Dealey Plaza? I am working on that now. I should have a new topic on this in a day or two.
No, they did not find two clusters of N-waves. Such a claim shows a lack of understanding of even the basics of the BBN and WA acoustical research for the HSCA.
The "separated by about a minute" comment is based on Mr. Elliott's debunked claim that the Decker "hold everything" crosstalk is a valid time indicator and thus proves that the dictabelt gunshot impulse patterns were recorded 60 seconds after the assassination.
No. My statement about other N-waves is not based on the “hold everything” crosstalk. It is Mr. Griffith who is misinformed. It is based on the statement made by Dr. Barger to the HSCA:
http://mcadams.posc.mu.edu/russ/m_j_russ/hscabarg.htm (http://mcadams.posc.mu.edu/russ/m_j_russ/hscabarg.htm)
You seem sincere here, but you are badly confused. Dr. Barger was talking about the waveforms after they were graphed and displayed on oscillograms and spectrograms. He was simply talking about how they appeared on the oscillograms and spectrograms and the analysis of their appearance before they began the screening tests. They had not even done the Dealey Plaza test firing yet. None of the screening criteria involved checking for N-waves and muzzle blasts.
The BRSW team began by listening to tape copies of the recordings of both police radio channels for general orientation. Because the recorders were sound-activated, they could have stopped frequently for varying amounts of time, except that the Channel I recorder ran continuously for 5.5 minutes when a transmitter, presumably on a police motorcycle, became stuck in the transmit mode (the Channel I recorder appears to have run continuously during the period of interest). Using the frequent annotations of time by dispatchers on both channels, BRSW estimated the approximate time of the beginning and end of this 5 1/2 minute stuck-button transmission. Because of the severe noise and distortion on the recording, the BRSW team could neither confirm that this segment contained gunshot sounds, nor eliminate the possibility that they were present, by simple listening or by examining the waveforms of sounds on the tape. Therefore, they went to Dealey Plaza in Dallas August 27, 1978, and made recordings of test shots with various kinds of guns and ammunition, two shooter locations, and many microphone locations along the approximate route of the motorcade. For each combination of shooter location and microphone location, there is a characteristic and complex pattern of echoes in the recording of the test shot, because after the first sounds travel by a direct path to the microphone (usually the bullet shock wave and the muzzle blast sound), subsequent sounds arrive (due to echoes from buildings and other large objects) with varying delays, depending on the length of the path they have taken. A typical test shot waveform, made with a shooter and 3 microphone locations close to those later claimed for an assassination shot from the knoll, is shown in Figure 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.
They had not even done the Dealey Plaza test firing yet?
This is the testimony from September 11, 1978:
https://archive.org/stream/HouseSelectCommitteeOnAssassinations/Volume%202_djvu.txt (https://archive.org/stream/HouseSelectCommitteeOnAssassinations/Volume%202_djvu.txt)
Below is the link I provided earlier, with just the September 11, 1978 testimony of Dr. James Barger.
http://mcadams.posc.mu.edu/russ/m_j_russ/hscabarg.htm (http://mcadams.posc.mu.edu/russ/m_j_russ/hscabarg.htm)
And a third link, showing the acoustic tests were run on August 27, 1978.
https://www.jfk-online.com/nas02.html (https://www.jfk-online.com/nas02.html)
So, actually the acoustic tests had already been run.
August 27, 1978: The Dealey Plaza firing tests were conducted and recordings of test rifle firings were made.
September 11, 1978: Dr. Barger testified that they had analyzed the data and gave the results of what they had found. And it was here that he talked about the two impulse sequences that they had found on the Dictabelt recording.
You keep making false statement after false statement and never acknowledge your previous mistakes.
And again, hear is the relevant passage:
Dr. Barger says that there were not one but two Impulse Sequences. They occur one minute apart.
First Impulse Sequence: 10.1 seconds long.
Second Impulse Sequence: Less than 5seconds long.
What was the difference between the two Impulse Sequences? The only explicit difference that Dr. Barger said was the length of the sequence. Since they were satisfied, from the Zapruder film that the shooting had lasted at least 5.6 seconds. So that factor alone eliminated the second sequence.
There is nothing in his testimony that there was a fundamental difference in these two sequences. That the first set of impulses were N-waves that could only be caused by shock waves, but the second set were of a completely different nature that could have been caused by ordinary sounds. From what Dr. Barger says, the two sequences were similar, just of different length, and on that basis alone, he discounted the second sequence.
Question:
Exactly where does Dr. Barger say, they carefully compared the first Impulse Sequence with the second Impulse Sequence? And found that the Impulses in the second sequence are nothing like the impulses in the first. And so, the impulses in the first sequence were, or mostly were gunshots, but the impulses in second sequence were not.
As far as I know, no just close study was ever done by Dr. Barger or anyone else.
My guess, is that you will dodge this question.
So, it appears that there are two impulse sequences in the 5.5-minute period when the transmitter key was stuck. And probably others on other portions of the tape.
Unbelievable. Just unbelievable.
The Dealey Plaza test firing was not conducted until BBN felt they had done as much screening and analysis as they thought could do without having test-firing data against which to compare the dictabelt data. At the time of the initial screening tests that Dr. Barger was discussing in his testimony, the test firing had not been done yet. BBN recommended that a test firing be done because of the results they had obtained from the screening tests.
Ok, I am done talking to Mr. Griffith on this issue. I will let other readers judge for themselves.
Here is the link that refers to the Dealey Plaza firing tests taking place on August 27, 1978 (second paragraph):
https://www.jfk-online.com/nas02.html (https://www.jfk-online.com/nas02.html)
Here is link to various testimonies over several days, including the September 11, 1978 testimony by Dr. Barger where he:
• Presents the work he and his team did on the Dealey Plaza firing tests in Exhibit F-367.
• Discusses finding two impulse sequences, separated by a minute, showing that an impulse sequence can be created, even without gunshots.
https://archive.org/stream/HouseSelectCommitteeOnAssassinations/Volume%202_djvu.txt (https://archive.org/stream/HouseSelectCommitteeOnAssassinations/Volume%202_djvu.txt)
And finally, a link to just the Dr. Barger testimony, which includes links to the figures he presented, including the all-important Exhibit F-367, which summaries the result of the August 27 Dealey Plaza firing tests, which Mr. Griffith keeps claiming have not been conducted yet.
http://mcadams.posc.mu.edu/russ/m_j_russ/hscabarg.htm (http://mcadams.posc.mu.edu/russ/m_j_russ/hscabarg.htm)
I’ll let the other members of this forum judge if I am telling the truth or him.
Mr. WEISS. In August of this year we examined the results of Dr. Barger's analysis up to that time, and also reviewed the plan for the reconstruction experiment to be conducted in Dallas and judged whether the experiment was necessary to be performed. We did visit Dr. Barger at his lab in Cambridge, Mass., and had a lengthy discussion with him, saw his result, and reported back to the committee that in our opinion the reconstruction experiment was not only fully justified but also necessary for the continuance of his analysis. (5 HSCA 556)
BBN was asked to examine the channel 1 Dictabelts and the tape that was made of them to see if it could determine: (1) if they were, in fact, recorded transmissions from a motorcycle with a microphone stuck in the "on" position in Dealey Plaza; (2) if the sounds of shots had been, in fact, recorded; (3) the number of shots; (4) the time interval between the shots; (5) the location of the weapon or weapons used to fire the shots; and (6) the type of weapon or weapons used.
BBN converted the sounds on the tape into digitized waveforms and produced a visual representation of the waveforms.(11) By employing sophisticated electronic filters, BBN filtered out "repetitive noise," such as repeated firings of the pistons of the motorcycle engine.(12) It then examined the tape for "sequences of impulses" that might be significant. . . .
Six sequences of impulses that could have been caused by a noise such as gunfire were initially identified as having been transmitted over channel 1.(13). . . .
These six sequences of impulses, or impulse patterns, were subjected to preliminary screening tests to determine if any could be conclusively determined not to have been caused by gunfire during the assassination. The screening tests were designed to answer the following questions:(14). . . . [The report then lists the six criteria, which I have quoted twice already.]
BBN next recommended that the committee conduct an acoustical reconstruction of the assassination in Dealey Plaza to determine if any of the six impulse patterns on the dispatch tape were caused by shots and, if so, if the shots were fired from the Texas School Book Depository or the grassy knoll.(16) The reconstruction would entail firing from two locations in Dealey Plaza--the depository and the knoll--at particular target locations and recording the sounds through numerous microphones. The purpose was to determine if the sequences of impluses recorded during the reconstruction would match any of those on the dispatch tape. If so, it would be possible to determine if the impulse patterns on the dispatch tape were caused by shots fired during the assassination from shooter locations in the depository and on the knoll. (HSCA Report, pp. 68-69)
The Committee decided to give this problem over to acoustics experts. These respected acoustics scientists would analyze the nature and origin of the suspect sound impulses on Channel 1 to determine if sounds of shots had been recorded; and if so, how many, the time interval, and point of origin. In May 1978 the Committee contracted with Bolt, Beranek and Newman, Inc. [BBN], to attempt the analysis. By means of sophisticated and, to the layman, complicated scientific analysis of the recordings, chief scientist Dr. James Barger located 6 impulse sequences which could have been caused by a loud noise such as a gunshot. The Committee was urged to conduct an acoustical reconstruction of the assassination at the Dallas site. Realizing that Barger's initial findings, if true, pointed to a probable assassination conspiracy, the Committee sought an independent review of his analysis by Queen's College, New York, professor Mark Weiss and his research associate, Ernest Aschkenasy. Barger's analysis and methodology for the reconstruction were concurred by the two others, and on August 20, 1978, an elaborate test in Dealey Plaza was conducted. (Trask, Pictures of the Pain, p. 131)
Here is link to various testimonies over several days, including the September 11, 1978 testimony by Dr. Barger where he:. . . .
• Discusses finding two impulse sequences, separated by a minute, showing that an impulse sequence can be created, even without gunshots.
I claim that there are at least two clusters of “impulsive patterns” in the 5.5-minute span when the microphone key was stuck on for Channel 1. These two clusters were separated by a minute of time, meaning that at least one of the clusters was not formed by gunfire. The basis for this claim is the testimony that Dr. Barger gave on September 11, 1978 to the HSCA:
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.
Your claim this is irrelevant, because the first cluster could only have been created by gunfire, while the second cluster was of a totally different nature.
Question:
Can you provide any sort of support for your claim? That the second cluster was carefully analyzed and the waveforms were totally different from the waveforms in the first cluster?
As far as I can tell, the only objection that Dr. Barger had to the second cluster, was that it covered too short a time period, under 5 seconds. Not that the waveforms themselves did not look like the waveforms that could be created by gunfire, or fundamentally different than the waveforms found in the first cluster.
If impulse patterns similar to those occurring at the time of the assassination were to be found anywhere else during the 5-minute recording of stuck transmission, then the patterns could safely be assumed to have been caused by something other than gunfire. Thus, we examined processed waveforms for the entire segment of stuck transmission, looking for impulse patterns similar to those already identified. During the course of this examination, only one other pattern was found. It began about 30 sec after the other four patterns and was comprised mostly of impulses apparently caused by radios keying in, attempting to transmit. This sequence, which lasted for approximately 4 sec, did not resemble the earlier impulse patterns well enough to have been caused by the same source. (8 HSCA 75)
Don’t try your usual trick of posting links to several different websites that are each very long, and implying the answer is to be found somewhere in there.
I’m looking for one website, and for you to copy and paste the short section that is relevant so anyone can do a simple text search to easily find this section, even in a very large webpage. Just give a simple short answer.
The dude is assigned to the presidential motorcade and doesn't even know which channel he's on, WTF?
Whoa! I'll answer your dumb question in a second, but I must ask: What happened to all of your jibberish about N-waves supposedly being scattered "throughout the dictabelt"? Is your silence on that topic a tacit admission that the claim is erroneous? And I see you're no longer claiming that I made the false statement that the Dealey Plaza test firing had not been done by the time Dr. Barger testified. That claim was yet another one of your embarrassing gaffes caused by your poor grasp of the HSCA's acoustical analysis.
Now, as for your dumb question: First of all, some of the links I've provided answer that dumb question. Furthermore, the BBN report answers that dumb question. Dr. Thomas answers that dumb question in his book. The fact that you would even ask this dumb question shows that you still don't even know the basics about the acoustical evidence.
Ok, I'll give you the short answer to your dumb question, and then I'll provide a quote to back up my answer.
The short answer is that, as I've told you several times now, the statement you keep quoting comes from when Barger was talking about the preliminary analysis. The second cluster, i.e., the later series of impulse events, that Dr. Barger was talking about was disqualified as gunfire in the preliminary analysis. It was disqualified because it failed to meet several of the screening criteria. It's mostly impulses of squawks caused by radios keying in.
As promised, and just to leave no room for honest, rational disputation on this issue, I am going to quote from the BBN report:
If impulse patterns similar to those occurring at the time of the assassination were to be found anywhere else during the 5-minute recording of stuck transmission, then the patterns could safely be assumed to have been caused by something other than gunfire. Thus, we examined processed waveforms for the entire segment of stuck transmission, looking for impulse patterns similar to those already identified. During the course of this examination, only one other pattern was found. It began about 30 sec after the other four patterns and was comprised mostly of impulses apparently caused by radios keying in, attempting to transmit. This sequence, which lasted for approximately 4 sec, did not resemble the earlier impulse patterns well enough to have been caused by the same source.
I have been talking about other things. But as to the other isolated impulses, I have heard they are there, that the sound like short bursts of static, similar to the “gunfire” second, just shorter. But it has been years seen I read that so I cannot site it. But at least we do have two examples of impulse sequences that even the BBN admit to on the 5.5-minute stretch of the stuck-key transmission, which is enough.
No, you have still not given me a sufficient answer. This quote is insufficient. What was it about the second cluster of impulses that caused the BBN to discount it? How could they tell the first cluster was made differently, while the second could only have been made by an attempt for someone else to transmit?
During the course of this examination, only one other pattern was found. It began about 30 sec after the other four patterns and was comprised mostly of impulses apparently caused by radios keying in, attempting to transmit. This sequence, which lasted for approximately 4 sec, did not resemble the earlier impulse patterns well enough to have been caused by the same source.
The two sequences did not resemble each other well enough. In what way?
Was it because the first cluster consisted of N-waves while the second of sin-waves?
Was it because the first pattern was 10.1 seconds long and the second was only 4 seconds long?
The BBN report does not explicitly say?
And again, to stress again, the BBN report says the two sequences were different. They make no claim that an individual impulse in the first sequence was fundamentally different than an individual impulse in the second sequence. Maybe they meant to say that. But they didn’t.
And let us make the unfounded assumption for the moment that an individual impulse was different in a fundamental way from one in the second. Would that alone be enough to conclude that both impulse sequences were not caused by someone keying in? Could not someone trying to key in over a radio in a police car produce different impulse patterns than someone trying to transmit over a motorcycle radio? Did both use the same type of radio? Could the distance from the radio receiver at headquarters make a difference, like 200 yards as opposed to 10 miles?
Even if the two impulse patterns do different in some fundamental way, other than the length of the time of the segments, we can’t conclude they were not both made by attempts of someone to transmit a short message, which are commonly 4 to 10 seconds long, as can been seen throughout the Dictabelt recording.
In any case, back to the main point, It seems, for all we know, the BBN reasons for discounting the second sequence of impulses were:
• All the shooting took place within about 10 seconds, so both sequences could not be gunfire.
• It was believed the shooting took place a span of any least 5 seconds, so the second sequence of 4 seconds could not have been the gunfire.
As far as I can tell, there are no other reasons for dismissing this second sequence. For all we know, if the same sort of comparison was made between the impulses of this second sequence with the Dictabelt, they would have found more pairs with a correlation coefficient of 0.6, 0.7 and 0.8. As far as I can tell BBN just assumed the first sequence might have been produced by gunfire and the second by someone attempting to transmit. As far as I can tell, BBN could have just as easily have made the opposite assumption.
Again, the only reasons this report explicitly gave for rejecting the second sequence of impulses were:
• It only covered 4 seconds.
There is nothing about the impulses in this second sequence being of a fundamental nature different than those of the first.
If there are addition reasons for rejecting this second sequence, the BBN report failed to spell them out.
So, as far as I can tell, they simply dismissed the second sequence as gunshots, because they only covered 4 seconds, and for that reason alone. Once that is assumed that, then they figured it must have been caused by something else, like someone trying to transmit a message. They may be right. But of course, maybe both sequences were caused by someone trying to transmit a message.
So, you keep complaining I keep answer for answers you already given, but I am going to continue to keep calling for answers until you can give a quality answer. Which, apparently, the BBN never provided.
This is idiotic stuff. You still haven't read the BBN report, the W&A report, and Thomas's book, have you?
Do I need to quote the accompanying paragraphs to establish that the context was the impulses that passed and did not pass the six screening tests? That's the context of the BBN report's statement that I quoted:
Because the second sequence failed several of the screening tests. That's because it was caused mostly by the squawking from radios keying in. It was not even close enough in its characteristics to have been caused by the same source as the impulse patterns that begin 2 seconds after Curry's "triple underpass" transmission and 2 seconds after Fisher's simultaneous "I'll check" crosstalk.
If there are no N-waves and muzzle blasts and muzzle-blast echoes, it ain't gunfire. If those things aren't present in the impulse sequence, then that sequence is not gunfire. Period. End of story. Rifle shots cause N-waves and muzzle blasts and muzzle-blast echoes. Nobody but nobody disputes this fact. So if an impulse pattern on a record does not contain any of these three characteristics, then it cannot be gunfire. Why can't you grasp this simple, basic point?
It's pretty clear on this if you read it with your brain turned on and if you have enough intelligence to understand the English. This part of the BBN report is discussing the first screening tests. It says the 4-second impulse sequence consists mostly of radios keying in. It says the sequence "did not resemble the earlier impulse patterns well enough to have been caused by the same source." So obviously it was not even a close call.
Then you can't read. The BBN report says the second impulse sequence "did not resemble the earlier impulse patterns well enough to have been caused by the same source" because it failed to pass the initial screening tests. If you read the surrounding text, this is crystal clear. An impulse sequence had to pass all six of the screening tests to warrant further analysis.
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 121/z after that, and so on, a definite 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. (2 HSCA 73-74)
Dr. BARGER. 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. (2 HSCA 18)
Dr. BARGER. Then we counted the number of impulses in each pattern of impulses that we see in the waveform records of the tape and we saw there were about 10. We realized there was still a possibility that these impulsive 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, any one 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 an acoustical 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. (2 HSCA 46-47)
It might help to point out that after BBN did the test firing in Dealey Plaza, they were able to perform more tests to identify gunfire sounds on the dictabelt. One of those tests was the matched filter test. Importantly, they applied this test to all the impulses on the dictabelt. No sound impulses that were recorded after Curry’s “to the hospital” transmission passed the matched filter test. Five of the six suspect sound impulses did pass the test. Here is some information about when and how BBN used the matched filter technique on the dictabelt, from Dr. Barger’s HSCA testimony:
No, they did not apply the “matched filter test” to all the impulses on the Dictabelt. Specifically, it was only applied to all the impulses on the first sequence of 10.1 seconds, not on the second sequence of 4.0 seconds that was recorded on the Dictabelt 30 seconds later.
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. (2 HSCA 73-74)
The “matched filter test” was comparing the 7 impulses from the first impulse sequence, covering 10.1 seconds, with the 2,408 impulses from the 1978 test with 69 rifle shots recorded on 36 microphones.
“Five out of six did passed the “match filter test”. First of all, it was seven impulses, not six. And only four of the seven passed, that is, had a correlation coefficient of 0.8 or higher. And the four that did pass, barely passed.
Six sequences of impulses that could have been caused by a noise such as gunfire were initially identified as having been transmitted over channel 1.(13) Thus, they warranted further analysis.
These six sequences of impulses, or impulse patterns, were subjected to preliminary screening tests to determine if any could be conclusively determined not to have been caused by gunfire during the assassination. . . .
All six impulse patterns passed the preliminary screening tests. (HSCA Report, p. 68)
But the main point is, the second sequence, the 4-second sequence, was never given the “matched filter test”.
For all we know, some of the impulses in that 4.0-second sequence would have passed as well, which would have served to discredit the BBN study.
But of course, the BBN study was discredited anyway, by their own data.
Check out the BBN’s Exhibit F-367 table which I have in my initial post of this thread. We don’t have a “match”, for a certain 1978 recreation shot, with both an impulse found in the Dictabelt 10.1-second and the 4.0-second sequence, because this test was never made. But we do have a couple of matches, for both the 137.70 and 145.61 Dictabelt shots, where matches of 0.8 correlation coefficient was found for a shot fired at two different targets. That shouldn’t happen. Each shot should have its own unique fingerprint. So, a correlation of 0.8 is not sufficient to say “We have a perfect match with this shot, fired from this location, at this target, recorded from this location” because they have two different shots that reach 0.8. Clearly a higher threshold than 0.8 was needed to make this determination, but the BBN could not find any.
Dr. BARGER. 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°
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 farther 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 impulse 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 approximated one; 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. 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 that did in fact exhibit a
correlation coefficient higher than 0.6. . . .
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.
Now a feature of a detection by a receiver 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.
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. . . .
Dr. BARGER. 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. . . .
Dr. BARGER. 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.
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 orderliness,
is 17 1/z . 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. . . .
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
are truth, then the motorcycle was going 18 miles an hour, catching
up with the limousine, and, in fact, having achieved a position
only 40 or 50 feet behind it at the time of the head shot.
Now, if you recall the first thing we noticed on the tape was that
there was a diminution of the sound due to the motorcycle 3
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° 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 right there,
and at the time of the last segment labeled No. 4, which at this
time we would estimate it to be halfway 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° 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. (2 HSCA 61, 63-69)
No matter which pattern matching methods where applied to locate the shots on Ch-1, the location of "Hold everything" cross talk captured on Ch-1 destroys any hope of the pulses actually being shots, according to O'Dell.
The argument is surprisingly simple and is explained by O'Dell in his article: http://mcadams.posc.mu.edu/odell/index.htm
Reference to Table 2 shows that five patterns passed the echo delay matching test. The five patterns are identified by their chronological position: 137.70, 139.27, 140.32, 145.15, and 145.61 seconds after the beginning of the motorcycle segment. One of the five, the pattern at 140.32 sec was judged to be a false alarm and discarded. This was the one glaring error in the acoustical analysis. The BBN Report states,
"The entry in Table II that occurred at 140.32 sec is a false alarm, because it occurred only 1.05 sec later than earlier correlations also obtained from the TSBD. The rifle cannot be fired that rapidly. Since there are three correlations plausibly indicating the earlier shot, the one occurring 1.05 sec later must be a false alarm."
The logic of this statement is that if it didn’t come from Lee Harvey Oswald’s rifle then, it was not a shot. But of course, the whole purpose of the inquiry was to test the Warren Commission’s single assassin theory against the facts, not the other way around. The fifth shot was dismissed because five shots were less palatable to the committee members than four shots. Palatability is not, however, a scientific criterion for judging the validity of evidence. Moreover, it was illogical to dismiss the pattern at 140.32 as a false positive because it was too close to the previous shot. The first two putative shots are only 1.7 sec apart, also too close together to have been fired from Lee Harvey Oswald’s rifle.
If the subject sounds are the assassination gunfire, and if three of the shots are attributable to Oswald’s rifle, then the second pattern is the rogue shot, not the third. But, the second pattern, at 139.27 sec, could not be dismissed as a false alarm because it was supported by multiple correlations, including a robust correlation coefficient of 0.8. The weakest supported pattern was the pattern at 140.32, with a score of only 0.6, and only one match, and was thus selected as the “false alarm.” The fact remains that five candidate patterns passed the initial screening tests, and all five matched to a significant degree with the test shot patterns. The time intervals between these putative shots, corrected for tape speed, were: 1.7, 1.1, 4.6 and 0.7 sec. (https://www.maryferrell.org/pages/Essay_-_Acoustics_Overview_and_History_-_part_2.html)
Five of those six impulse patterns passed the matched filtering test.
Oh. . . . Okay. . . . So all the BBN scientists were involved in a conspiracy to lie about the 4-second impulse. LOL. Got it.
Here's a question to chew on: The NRC panel had unlimited funding and could have easily tested that 4-second sequence with all the tests that the HSCA experts applied to the six gunshot sequence patterns that passed the screening tests. Why didn't they do that? Because they knew it would be a waste of time?
First of all, a correlation of 0.8 is very high, very close to perfect, as Barger explained. 0.5 was the minimum threshold, although Dr. Barger mostly limited his discussion to correlations that were at least 0.6, for reasons that Barger also explained. Dr. Barger said that a correlation of 0.75 meant that two impulse patterns matched "quite admirably." So 0.8 is a very solid correlation.
| Test | Beginning Time of | Zap. | Zap. | Microphone Array | Rifle | Target | Correlation | Strong | Fluke |
| ID | First impulse on | Frame | Frame | and | Location | Location | Coefficient** | ||
| Tape Segments (sec) | BBN | Thomas | (Channel Numbers) | ||||||
| B | 137.70 | 168 | 176 | 2 ( 5 ) | TSBD* | 1 | 0.8 | Strong | |
| D | 137.70 | 168 | 176 | 2 ( 6 ) | TSBD | 3 | 0.8 | Strong | Fluke |
No matter which pattern matching methods where applied to locate the shots on Ch-1, the location of "Hold everything" cross talk captured on Ch-1 destroys any hope of the pulses actually being shots, according to O'Dell.
The argument is surprisingly simple and is explained by O'Dell in his article: http://mcadams.posc.mu.edu/odell/index.htm
From the article, section named "Synchronization", this is what it boils down to:
(My emphasis, click on Fig. 2 for a better image)
Any pair of events on Ch-2 can never have been spaced closer in real time that on the tape, that's why the 61 second is the best one can hope for. IMO, the only way to push the time of the shots back towards 12:30 is to show the recording was paused between shots and "HOLD...".
The "ALL right Chaney" event is not marked on Fig. 2. From what I've seen this is supposed to be the alleged Fisher cross talk "I'll check it" which is disputed by others. To be looked further into....
Sigh. . . . That's because it failed the initial screening tests in the preliminary analysis! Sheesh, we've been over this already. Hello? That sequence is mostly a bunch of squawks from radios keying in. It was judged to be too dissimilar to the suspect impulse patterns to warrant further analysis.
Is “mostly a bunch of squawks” Dr. Barger’s description or yours? Where does Dr. Barger say, in some many words, that this particular impulse sequence, of 4-seconds, was a bunch of “squawks”, or words to that effect. And yes, he does give the opinion that this 4-second impulse sequence was caused by someone trying to key in, but where does he give evidence to support this opinion?
From what I have read, Dr. Barger rejects this 4-second sequence of impulses, because it was shorter than 5-seconds.
The recorded outputs from both filters for the full 5 minutes were compared, examined, and plotted on a scale where 5 in. equals 1/10 sec. These plots revealed five impulse patterns introduced by a source other than the motorcycle. Upon closer examination, all but one of these patterns were sufficiently similar to have had the same source, and the impulses contained in these patterns appeared to have shapes similar to the expected characteristics of a shock wave and of a muzzle blast. The remaining pattern was sufficiently different in amplitude and duration as to have been caused by a different source. (8 HSCA 43)
And, yes, Blakey did pressure BBN to reject the 140.3 shot on non-acoustical grounds--again, for the third or fourth time, Dr. Barger admitted to Dr. Thomas that the 140.3 shot was rejected based on a circular argument and an "ad hoc" criterion. This is all discussed in Dr. Thomas's section on the 140.3 shot. I should add that Blakey himself admitted to Dr. Thomas that he did not want to accept the 140.3 shot because he knew he was going to take tremendous heat just for saying the dictabelt contained four gunshots, and because he feared that the fifth shot would dilute the case for four shots.
As for your continued polemic about F-367, I'm not going to waste time repeating why your characterization of it is misleading. Dr. Thomas spends six pages discussing the facts surrounding the 140.3 gunshot impulse (Hear No Evil, pp. 587-593). Go read it, and then come back and tell me there were valid grounds for rejecting it. 0.6 was a deliberately high threshold to eliminate as many false alarms as possible without also missing gunfire, and the 140.3 shot met that threshold.
And, yes, Blakey did pressure BBN to reject the 140.3 shot on non-acoustical grounds--again, for the third or fourth time, Dr. Barger admitted to Dr. Thomas that the 140.3 shot was rejected based on a circular argument and an "ad hoc" criterion. This is all discussed in Dr. Thomas's section on the 140.3 shot. I should add that Blakey himself admitted to Dr. Thomas that he did not want to accept the 140.3 shot because he knew he was going to take tremendous heat just for saying the dictabelt contained four gunshots, and because he feared that the fifth shot would dilute the case for four shots.
That is just stupid. Saying there were four shots, three from the TSBD, one from the Grassy Knoll, is something Blakey can handle. But saying there were five shots, four from the TSBD, one from the Grassy Knoll, that’s going to get Blakey in too much trouble. He’ll be taken out by the men in black within the week.
There are clear problems with the BBN’s chart, Exhibit 367 (shown at my initial post of this thread). [MORE MISLEADING, CONFUSED DRIVEL SNIPPED]
| Test | Beginning Time of | Zap. | Zap. | Microphone Array | Rifle | Target | Correlation | Strong | Fluke |
| ID | First impulse on | Frame | Frame | and | Location | Location | Coefficient** | ||
| Tape Segments (sec) | BBN | Thomas | (Channel Numbers) | ||||||
| L | 145.15 | 304 | 313 | 3 ( 4 ) | KNOLL | 3 | 0.8 | Strong | |
| M | 145.15 | 304 | 313 | 3 ( 7 ) | TSBD* | 4 | 0.7 | Fluke | |
| N | 145.15 | 304 | 313 | 3 ( 8 ) | TSBD | 2 | 0.7 | Fluke | |
Oh, my! I see that you snipped the part of my reply where I proved that the 4-second impulse pattern is a dead end, a non-issue. You've been droning on and on about that pattern and about how it supposedly proved that the HSCA experts ignored other valid gunshot-like patterns on the dictabelt. And I've been telling you over and over that the pattern was rejected because it failed more than one of the initial screening tests in the preliminary analysis, but you kept saying, "Gee, as far I can tell, it was only rejected because it wasn't long enough." But now that I have proved from the BBN report that the pattern failed two of the five screening tests and that it contains no N-wave and muzzle-blast patterns, you go silent on the subject.
The 4-second sequence failed two of the screening tests, not just one. It failed the duration test, and it also failed the amplitude test.
The recorded outputs from both filters for the full 5 minutes were compared, examined, and plotted on a scale where 5 in. equals 1/10 sec. These plots revealed five impulse patterns introduced by a source other than the motorcycle. Upon closer examination, all but one of these patterns were sufficiently similar to have had the same source, and the impulses contained in these patterns appeared to have shapes similar to the expected characteristics of a shock wave and of a muzzle blast. The remaining pattern was sufficiently different in amplitude and duration as to have been caused by a different source. (8 HSCA 43)
This is not a serious answer. Five shots is 25% more than four shots and 33% more than three shots. Plus, you omitted the fact that acknowledging the fifth shot would have also required admitting that there was another gunman firing from behind. So it is not at all "just stupid" that Blakey did not want to admit that five shots were fired. It was wrong and misleading, but it was not "stupid."
This is similar to your silly answer when I made the factual point that the NRC panel had ample funding to conduct the same tests on the 4-second pattern that the HSCA did on the gunshot impulse patterns. Doing those tests would not have cost a lot of money, and the NRC panel had all the time in the world to get them done. But, they declined to do so. Why? Probably because they knew it would be a waste of time, because they, unlike you, had at least read the HSCA materials, and so they knew that the 4-second pattern had been rejected on entirely valid grounds.
And Dr. Thomas has been dishonest about the sirens heard on the Dictabelt, implying you can hear them loudly all the way to the hospital, when in truth, you don’t hear them, then they gradually get louder, and then fade away, as if recorded from a stationary motorcycle at the Trade Mart Center.
Can you provide a link to the audio recording where you are hearing this?
I'm currently looking at Fig 22 on page 63 where "false alarms" are marked with an X,
https://www.history-matters.com/archive/jfk/hsca/reportvols/vol8/html/HSCA_Vol8_0054a.htm
If you read on it's a simple fact they have have false alarms and they document them as they should.
In line with the fingerprint analogy proposed by Barger, for each acoustical fingerprint, they're now left them with several suspects, some of which are in fact false suspects. As I understand the explanations even more would have been acceptable and it's to some degree (lost reference) due to the spacing of the microphones. The further apart the worse the quality of detection becomes.
A pretty crazy example is #1, on top of page 65, at 137.70.
Even though the tape has already been screened and filtered they need to do further cleansing using additional "logic".
However, the expected number of false alarms [[false positives]] to be found when testing four different impulses patters is 13 (see Appendix C), and only six [[false positives]] have been found. Therefore, it is not unreasonable to expect that there are seven more [[false positives]], although that would be the largest number possible since at least two of the remaining nigh are probable detections [[true positives]].
https://mcadams.posc.mu.edu/dpdtapes/ (https://mcadams.posc.mu.edu/dpdtapes/)
It is a 2:41 (two minutes, forty one seconds) recording at around 12:30.
Click on the little “speaker” and it may say you need to download Realplayer, which I did. It was fairly straight forward. I would prefer it was on youtube.
But yes, around 1:20 into the 2:41 recording, the sirens start up, build up and fade away by 1:57. I hear no more sirens from then on and the recording goes about another 44 seconds.
Thanks. Here's the direct link to the audio file for anybody else who might be interested.
https://mcadams.posc.mu.edu/dpdtapes/capture24.ram (https://mcadams.posc.mu.edu/dpdtapes/capture24.ram)
I definitely hear the sirens. Whether they "gradually get louder, and then fade away, as if recorded from a stationary motorcycle at the Trade Mart Center" seems to be a bit of an interpretive stretch.
In any case, I caught up with and got in front of the limousine on Stemmons somewhere around Continental. The ride was wild! You know in your mind that you’re going way too fast, but if you slow down or fall, the cars behind are going to run over you. But you don’t think about those things, though, at the time; it’s all instinct.
We had to slow down when we got off Stemmons at Industrial. Along Industrial there was a railroad track which was located on a small incline some twenty to thirty feet before we were to hit Harry Hines Boulevard. Chaney, myself and another officer went airborne up the incline, hit the ground, and made the sharp left onto Hines.
When we arrived at the hospital, I parked my motorcycle and came back to the limousine about fifteen feet away. As the hospital orderlies approached to take him out of the car, Mrs. Kennedy was still laying over him, covering his head, and wouldn’t get up. So, I took it upon myself, reached over and caught her by the shoulder, pulled her and said, “Come on, let them take him out.” Somebody threw a coat over him just as she raised up, and they took him out on the right side of the car. She then stepped out on the left, stunned, and walked with me in a daze into the emergency room.
• It is known that police motorcycles were waiting at the Trade Mart Center.
• The limousine passed within 200 yards of the Trade Mart Center.
• The phrase “Attention all units” heard on the Dictabelt was not broadcast by the Dallas police dispatcher, because it is not recorded on Channel 2. But it could have been the Dallas county sheriff dispatcher, and none of their vehicles were escorting the motorcade but some were waiting at the Trade Mart Center.
• The sound of someone whistling does not fit with a motorcycle speeding off the Parkland, but does fit a motorcycle waiting at the Trade Mart Center.
Where do you hear the phrase "attention all units"?
Where do you hear "the sound of someone whistling"?
How does whistling indicate Trade Mart anyway?
How do you know the 2:41 excerpt was continuously recorded and is complete? I hear "clear 12:34" twice in the excerpt. Once at 2:23 and then again softer at about 2:32.
This is very difficult to hear. Like the phrase “Hold everything secure”. But I here some brief phrase of “. . . all . . .” right at 2:00. But, admittedly, this is very difficult to make out.
In several parts, but most clearly at 1:02, just after someone says “1 2 3 4”. It only lasts a couple of seconds, but is clearly a brief tune, not just a tone of some sort.
It is a very strong indicator of a motorcycle not with the motorcade, not escorting the Presidential limousine at high speed to the Parkland Hospital.
Because as long as the microphone button is stuck, it will keep recording continuously. It only stops recording if no one is transmitting anything. The phrase “clear 12:34” might be repeated twice in 9 seconds, in case the officer didn’t think his first message got through.