Understanding and Appreciating the HSCA Acoustical Evidence

[Michael Griffith]

Some conspiracy theorists reject, minimize, or ignore the HSCA acoustical evidence only because they believe it does not support their shooting scenario, even though it refutes the lone-gunman theory. Specifically, they do not accept the duration and timing of the shots on the police dictabelt and/or they think the tape requires them to believe that only four shots were fired, that three of those shots came from the TSBD's sixth-floor southeast corner window, and that only one shot came from the grassy knoll. 

However, the acoustical evidence does not require acceptance of all of these positions. It is crucial to understand that the four impulse patterns that the HSCA acoustical experts identified as shots on the police tape were identified as gunfire because they matched the impulse patterns of four shots fired during the HSCA field test in Dealey Plaza, and that during that test, shots were fired from only two locations: the sixth-floor window and the grassy knoll.

During the HSCA test firing, no shots were fired from any window in the Dal-Tex Building or the County Records Building, or from any other alternative point in the plaza, but only from the sixth-floor window and from a spot behind the picket fence on the grassy knoll.

In addition, a fifth impulse pattern on the dictabelt was arguably wrongly rejected as gunfire. Due to pressure from the HSCA, the BBN experts identified the impulse pattern at 140.32 as a false alarm, even though it passed the echo-delay matching test, and even though 8 of its 10 impulses matched the impulses of one of the test shots. The BBN experts said they rejected this impulse pattern as a shot because it occurs just 1.07 seconds after the second shot from the sixth-floor window, and because it "only" had one microphone match and "only" had a coefficient score of 0.6. A coefficient score of 0.6 means that 8 of the 10 impulses in the impulse pattern matched the impulses of a pattern of one of the field-test shots. The rejection of the 140.32 impulse pattern as gunfire seems to have been based on something other than science. As Dr. Don Thomas says,

          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.  (https://www.maryferrell.org/pages/Essay_-_Acoustics_Overview_and_History_-_part_2.html)

Furthermore, if there was a third gunman and he used a silencer or fired from a point five or six feet behind a window, even if the HSCA field test had fired shots from his location or from a nearby location, either his shots would have created no impulse patterns on the tape or they would have created patterns that were too weak to be matched to test-shot patterns. 

Edited June 26, 2023 by Michael Griffith

[Michael Griffith]

Of course, some conspiracy theorists reject the acoustical evidence because they believe it has been refuted by the Decker "hold everything" crosstalk and/or by the inability to positively identify which motorcycle recorded the sounds on the police tape. These have never been good arguments against the acoustical evidence because they ignore the truly remarkable evidentiary correlations documented by the HSCA acoustical experts.

We can start with the fact that gunfire N-waves, muzzle blasts, and muzzle-blast echoes are recorded on the tape.  In addition, the N-waves only occur among the identified gunshot impulses and only when the motorcycle's microphone was in position to record them. This is a stunning correlation. But it gets better: the N-waves, muzzle blasts, and muzzle-blast echoes also occur in the correct order and interval. Try to fathom the odds that these correlations are merely coincidences among sounds caused by human speech, as some critics have amateurishly claimed. 

I think these correlations alone prove that some microphone in Dealey Plaza must have recorded the impulses, because N-waves, muzzle blasts, and muzzle-blast echoes do not just magically appear on recordings out of thin air, much less in the correct order and interval. In his article "The Bike with the Mike," Dr. Don Thomas makes a credible case that McClain's bike was the bike with the open microphone, and in the process he responds to Dale Myers' claims about McClain's position (https://www.maryferrell.org/pages/Essay_-_The_Bike_With_the_Mike.html). 

The HSCA experts from BBN knew that if they were dealing with impulse patterns caused by gunfire, each of the sounds would come in a specific order: they knew that the N-wave would come first, followed by the muzzle blast, followed by echoes of the shock wave and the muzzle blast. They also knew that the presence of these patterns would depend on whether the microphone was in position to record them. 

The BBN scientists screened all of the impulse patterns on the police tape for N-wave-like characteristics (some critics have wrongly claimed that only certain patterns were screened). Keep in mind, too, that the BBN experts did not have the test-firing data yet, so they did not know that those data would powerfully support the presence of gunfire on the tape.

But even without the field-test data, being acoustical scientists, they understood the general characteristics of N-waves and how they would appear on an oscillogram printout of a recording. And they found that the N-waves, muzzle blasts, and muzzle-blast echoes only occur among the identified gunshot impulse patterns, and that they occur in the correct order and interval. By the way, the NRC panel--aka the NAS panel--did not lay a finger on this impressive evidence.

The NRC panel also failed to address the remarkable windshield- distortion correlations. The HSCA experts tested for the effect of windshield distortions and then analyzed the dictabelt to see if such distortions were recorded on the tape. They not only found that windshield distortions occur in the police tape's gunshot impulse patterns but that they only occur when the motorcycle was in position to allow them to occur, and that they do not occur when the motorcycle was not in position to allow them to occur. Again, the NRC panel did not even attempt to explain these correlations.

The HSCA experts proved that at least four of the gunshot impulses on the dictabelt recording have echo patterns that are unique to Dealey Plaza (incidentally, the rejected fifth gunshot at 140.32 also passed the echo-correlation or echo-delay test). Critics can offer no plausible explanation for these echo correlations. These correlations are the reason that acoustical expert Aschkenasy noted that if the police microphone did in fact record the sounds on the tape in a different location, that location would have to be an exact replica of Dealey Plaza.

The HSCA acoustical experts found remarkable timing-movement correlations between the five suspect dictabelt impulses and five Dealey Plaza test shots. Not only do they match in sequence, but they also match in spacing and distance. The sequence match alone is impressive, since there are 120 ways to order five events. The odds of randomly ordering five events in the correct sequence are 1 in 120, or less than 1%, and this is not considering the correlations in spacing and distance. Even the NRC panel obliquely admitted that their own calculations showed that the odds that these correlations resulted from chance were only 7%. And, even the hard-nosed historian Dr. David Kaiser finds these timing-movement correlations impressive and impossible to dismiss.

And we should remember that sonar analysis enabled Weiss and Aschkenasy to reduce the acceptance window for matching a dictabelt impulse with a test-firing shot from 6 milliseconds down to 1 millisecond, a 500% narrower window, which vastly reduced the possibility of a false match for the grassy knoll shot. 1 millisecond is one one-thousandth of a second. To be counted as a match, a dictabelt impulse and a test-shot echo pattern had to correspond to each other within the incredibly short timeframe of 1 millisecond

As for the Decker "hold everything" crosstalk transmission, this has never been a good argument because the Decker transmission is not a reliable time indicator, much less a determinative one. The time offsets alone indicate that the "hold everything" transmission is not a reliable time marker. Other transmissions are more compelling time markers, and they show that the shots occurred at the correct time. Critics have ignored these other transmissions, even though (or because) they all show the gunshot impulses were recorded during the assassination, and instead they have accepted the lone Decker transmission as determinative.

One of those other transmissions is also a crosstalk transmission. It is Deputy Chief Fisher’s “I’ll check” transmission, which occurs 2 seconds before the first dictabelt gunshot on Channel 1, and about 8 seconds before the 12:30 time notation on Channel 2. The Fisher crosstalk puts the time of the dictabelt gunshots during the assassination. Ironically, critics claim that the Fisher transmission is not crosstalk, even though the Dallas police officers who prepared the transcripts of the tape cited it as a prime example of crosstalk.

And then there's Chief Curry’s “triple underpass” transmission, which occurs 6 seconds before the 12:30 time notation on Channel 2 and 2 seconds after Deputy Chief Fisher’s “I’ll check” transmission. Chief Curry’s “triple underpass” transmission and the first dictabelt gunshot occur virtually at the same time. Curry’s “to the hospital” transmission occurs 12 seconds after the 12:30 time notation on Channel 2. This is key evidence because we know that Curry made the “to the hospital” transmission while still in Dealey Plaza, shortly after he heard gunfire. 

I think the tests that Josiah Thompson arranged to have done at BBN prove once and for all that the Decker "hold everything" crosstalk is not a valid time indicator but is a meaningless anomaly. Thompson discusses these tests and their results in great detail in his recent book Last Second in Dallas. By the way, his book includes two analyses written by BBN acoustical experts.

Edited June 28, 2023 by Michael Griffith

[Ron Ecker]

As I recall, the FBI conducted a study or "investigation" that it claimed debunked the acoustical evidence. Based on what I don't know, but it served its purpose. With respect to the JFK assassination, of course, FBI stood for Federal Bogus Investigations.

 

 

[Charles Blackmon]

Have any researchers or paid specialists tried to correlate the first gunshot impulse on the tape with a frame or frames on the Zapruder film?

[Michael Griffith]

2 hours ago, Ron Ecker said:

As I recall, the FBI conducted a study or "investigation" that it claimed debunked the acoustical evidence. Based on what I don't know, but it served its purpose. With respect to the JFK assassination, of course, FBI stood for Federal Bogus Investigations.

You are referring to the first critique of the acoustical evidence. It was written by FBI agent Bruce Koenig. Simply put, Koenig didn't know what he was talking about. He apparently did not even read the BBN report, or else he didn't understand it or purposely misrepresented it, and he clearly had no clue about Weiss and Aschkenasy's analysis. 

2 hours ago, Charles Blackmon said:

Have any researchers or paid specialists tried to correlate the first gunshot impulse on the tape with a frame or frames on the Zapruder film?

That is a problematic exercise because of the factors I discuss in the first post. One factor is that since the field test only fired shots from the sixth-floor window and a spot on the grassy knoll, there were no impulse-pattern data on shots from other locations. 

There is also the fact that there are strong indications that the Zapruder film was edited shortly after the assassination. 

Edited June 27, 2023 by Michael Griffith

[Michael Griffith]

10 hours ago, Charles Blackmon said:

Have any researchers or paid specialists tried to correlate the first gunshot impulse on the tape with a frame or frames on the Zapruder film?

Just to follow up on my previous answer, the following segment from the BBN final report to the HSCA helps explain why the dictabelt does not necessarily contain detectable impulses from every shot that was fired in Dealey Plaza during the assassination. After explaining the acoustical characteristics of radio-transmitted gunfire sounds (N-wave, muzzle blast, shock wave, etc.), the report explains that only the "very loudest" sound impulses would be loud enough to be heard (and detected) over the noise of the motorcycle's engine:

          All sound impulses arriving at the microphone that are loud enough to be heard over the environmental noise would be transmitted over the radio connected to the microphone. In this case, the environmental noise consisted primarily of the very loud, repetitive noise made by the engine of a moving motorcycle. This noise was found to be only about 10 dB lower than the loudest gunfire impulse recorded. Thus, only the very loudest gunfire sound impulses would actually be detectable above the engine noise. (8 HSCA 55, p. 15 in the BBN report)

The BBN report also explains that the loudest gunfire sound impulses are much louder than human speech:

          The loudest sound impulses from gunfire are considerably louder than the loudness of speech, for which the radio was designed to operate. (8 HSCA 55, p. 15 in the BBN report)

I point this out because a few WC apologists have floated the claim that the N-waves, muzzle blasts, and muzzle-blast echoes on the police tape were caused by human speech.

[Pat Speer]

It's ironic, Michael, that you are pushing this after vilifying me for disagreeing with Mantik. Mantik, to be clear, is one of the few prominent researchers to publicly dispute the acoustics evidence. This has led to some interesting situations for me personally. I was at a conference where David spoke against the acoustics evidence, where people, knowing of our disagreements on the medical evidence, came up to me and said David was--to be nice--totally incorrect about the acoustics evidence. Well, these people were shocked to hear me say I largely agreed with him on this issue. 

 

Edited June 28, 2023 by Pat Speer

[Michael Griffith]

18 hours ago, Pat Speer said:

It's ironic, Michael, that you are pushing this after vilifying me for disagreeing with Mantik. Mantik, to be clear, is one of the few prominent researchers to publicly dispute the acoustics evidence. This has led to some interesting situations for me personally. I was at a conference where David spoke against the acoustics evidence, where people, knowing of our disagreements on the medical evidence, came up to me and said David was--to be nice--totally incorrect about the acoustics evidence. Well, these people were shocked to hear me say I largely agreed with him on this issue. 

 

Dr. Mantik and I have had several discussions about the acoustical evidence. I would be hesitant to challenge his view on an issue regarding optical density measurements of the skull x-rays, since that is his field of expertise. But acoustics is not his field of expertise, and in this case he is simply wrong.

He views all of the evidentiary correlations identified by the HSCA experts--windshield distortions at the correct time, N-waves and muzzle effects only among the gunshot impulses and in the correct order and interval, echo patterns identical to those of Dealey Plaza, etc.--as coincidences. Mantik and I greatly respect each other, but I have frankly told him that I find it impossible and incredible to regard those correlations as mere coincidences. We have cordially agreed to disagree on this.

Mantik relies on Michael O'Dell as an acoustical expert. In fact, he considers O'Dell the "reigning expert on the acoustics evidence." Those who know about O'Dell's shoddy work on the RFK acoustics know that O'Dell is no acoustical scientist, and Don Thomas has refuted O'Dell's research on the HSCA acoustical evidence. 

I do not claim to be an acoustical scientist, but I did spend 21 years working in the field of signals intelligence in the Army, and in that capacity I received technical training on radio theory, radio-wave propagation, the effects of weather on radio transmissions, types of signals, radio-wave modulation, characteristics of wave travel, characteristics of frequency bands, etc. At times I also had to actually use radio systems, some of which were rather old. So, while I am no acoustical scientist and do not pretend to be, I do know a little bit more about the subject than your Average Joe.

Mantik also relies on the badly flawed Sonalysts critique. Some of the Sonalysts analysts' errors are so basic as to be embarrassing. For example, they argue that the HSCA acoustical scientists should have put more emphasis on the amplitude of the sound impulses, not just on their timing. This argument indicates a lack of understanding about how the police dispatch system’s automatic gain control (AGC) circuit worked. The AGC, like other AGCs, did not just suppress loud sounds; it also amplified weak sounds. This argument also ignores the fact that windshield distortion would have reduced the strength of some of the recorded sound impulses.

One of Mantik's issues with the acoustical evidence is Thompson's attempt to align the gunshot impulses with events in the Zapruder film. But the police tape is not a comprehensive audio record of the shots fired during the assassination, for the reasons I've explained earlier in this thread, so any attempt to match the shots with reactions in the Zapruder film is problematic from the outset.

This brings us to another flaw in Mantik's arguments against the acoustical evidence:  he assumes that if the dictabelt was recorded in Dealey Plaza during the shooting, it must contain all the shots that were fired. Thus, for example, in responding to Josiah Thompson, he makes the false-choice argument that "Either accept (per SSID) two head shots in quick succession (Z-312 to Z-313)— or accept the acoustic sequence, which requires a single (frontal) shot at about Z-312 and then a later shot (from the rear) at Z-328" and "JT can no longer tolerate any (not even one inch) actual forward head displacement at Z-313—because it violates his acoustic case." 

Many defenders of the acoustical evidence, including Thompson, wrongly assume that the tape contains all the shots that were fired, but it most certainly does not. Thompson and others should know this, given that the HSCA field test only fired shots from two locations in the plaza, and given that any shots that were not as loud as the engine noise would be undetectable on the dictabelt.

My bottom line is this: Okay, if you are certain that there was no motorcycle in position to record the sounds on the police tape during the shooting and/or that the sounds were recorded after the assassination and not in the plaza, then, for starters, you need to give me a rational, believable explanation for (1) how N-waves, muzzle blasts, and muzzle-blast echoes occur on the tape at the correct time (i.e., only during the putative gunshot impulses) and in the correct order and interval, (2) how windshield-distortion patterns occur on the tape and only when the microphone was in position for them to occur and never when the mike was not in the correct position, and (3) how the echo patterns of the identified gunshot impulses on the tape match the echo fingerprint of Dealey Plaza. Again, this is just for starters. 

Edited June 28, 2023 by Michael Griffith

[Tom Gram]

25 minutes ago, Michael Griffith said:

(2) how windshield-distortion patterns occur on the tape and only when the microphone was in position for them to occur and never when the mike was not in the correct position

Isn’t this aspect screwed up by McClain not being in the right spot? 

[Michael Griffith]

2 hours ago, Tom Gram said:

Isn’t this aspect screwed up by McClain not being in the right spot? 

This question both misses and avoids the point. Let me ask you a question in response: Why do windshield-distortion patterns occur on the police tape and only occur when the microphone was in position to allow them to be recorded and never when the mike was not in the correct position? How did those intricate sound patterns get on the tape?

The HSCA acoustical experts first conducted a field test for windshield distortion. Once they confirmed the phenomenon and had impulse-pattern data on it, they examined the police tape for patterns of windshield distortion and found them--not only found them but found that they occurred when they should and did not occur when they should not have. The HSCA's final report provides a good summary on this:

          Weiss and Aschkenasy also considered the distortion that a windshield might
cause to the sound impulses received by a motorcycle microphone. They reasoned that the noise from the initial muzzle blast of a shot would be somewhat muted on the tape if it traveled through the windshield to the microphone. Test firings conducted under the auspices of the New York City Police Department confirmed this hypothesis. Further, an examination of the dispatch tape reflected similar distortions on shots one, two, and three, when the indicated positions of the motorcycle would have placed the windshield between the shooter and the microphone. On shot four, Weiss and Aschkenasy found no such distortion. The analysts' ability to predict the effect of the windshield on the impulses found on the dispatch tape, and having their predictions confirmed by the tape, indicated further that the microphone was mounted on a motorcycle in Dealey Plaza and that it had transmitted the sounds of the shots fired during the assassination. (HSCA report, pp. 74-75)

There is a reason that the NRC panel, as determined as they were to debunk the acoustical evidence, did not even mention, much less address, these remarkable correlations.

Some motorcycle in the plaza recorded those sounds.

Have you read Dr. Thomas's rebuttal to Myers on McClain's position during the time in question?

Edited June 28, 2023 by Michael Griffith

[Denny Zartman]

Good posts @Michael Griffith

[Pat Speer]

On 6/28/2023 at 6:44 AM, Michael Griffith said:

This question both misses and avoids the point. Let me ask you a question in response: Why do windshield-distortion patterns occur on the police tape and only occur when the microphone was in position to allow them to be recorded and never when the mike was not in the correct position? How did those intricate sound patterns get on the tape?

The HSCA acoustical experts first conducted a field test for windshield distortion. Once they confirmed the phenomenon and had impulse-pattern data on it, they examined the police tape for patterns of windshield distortion and found them--not only found them but found that they occurred when they should and did not occur when they should not have. The HSCA's final report provides a good summary on this:

          Weiss and Aschkenasy also considered the distortion that a windshield might
cause to the sound impulses received by a motorcycle microphone. They reasoned that the noise from the initial muzzle blast of a shot would be somewhat muted on the tape if it traveled through the windshield to the microphone. Test firings conducted under the auspices of the New York City Police Department confirmed this hypothesis. Further, an examination of the dispatch tape reflected similar distortions on shots one, two, and three, when the indicated positions of the motorcycle would have placed the windshield between the shooter and the microphone. On shot four, Weiss and Aschkenasy found no such distortion. The analysts' ability to predict the effect of the windshield on the impulses found on the dispatch tape, and having their predictions confirmed by the tape, indicated further that the microphone was mounted on a motorcycle in Dealey Plaza and that it had transmitted the sounds of the shots fired during the assassination. (HSCA report, pp. 74-75)

There is a reason that the NRC panel, as determined as they were to debunk the acoustical evidence, did not even mention, much less address, these remarkable correlations.

Some motorcycle in the plaza recorded those sounds.

Have you read Dr. Thomas's rebuttal to Myers on McClain's position during the time in question?

Have you read my article on the photo evidence regarding the shooting? I hate to say it but Dale Myers is right. And McLain was telling the truth. He was not where the acoustics experts claimed he would have to have been at the time of the first shot. 

I was asked to provide my analysis to Tink and co. while his book was in preparation. I did so. Evidently they felt the best way to avoid the obvious was to not mention it. The films and photos prove McLain was not where they said he was. I will not dismiss the acoustics altogether because it could be that a different mic at a different location could record a similar impulse. But it certainly looks like the whole thing is junk science. I mean, the HSCA report used a still from the Dorman film to prove McLain was in the proper position, but that still was taken 20 or more seconds later. Don Thomas tried to counter this by moving the first shot to a later time. But his claims are equally problematic, as he has McLain traveling something like 4 mph across the plaza, hiding behind this car than that car etc, so there is no photo of him crawling across the plaza.

What we have instead is this... 

McLain is at far left. Note that Dave Wiegman is filming the Newmans. Well, when one studies the Wiegman film one realizes that this moment occurs towards the end of his film, so this is something like 30 seconds after the first shot. Now, the acoustics experts claimed the motorcycle traveled at a consistent speed across the Plaza--I believe they estimated 11 mph. This speed supposedly put McLain in the proper position to be in place for the sound signature of each sound on the recording. And yet here he is, just passing Wiegman, a cameraman who ran from a car after the first shot, a cameraman who has been on the knoll for a number of seconds. 

Now get this. The acoustics experts claimed they identified the location of Mclain's mic at the time of the first shot. And, golly, this location was roughly two cars ahead of Wingman's location at this time. So, yeah, to subscribe to the HSCA acoustics analysis means you believe Wiegman, carrying a heavy camera, not only raced past McLain, who was riding a motorcycle, but passed him so rapidly he had time to film the scene on the knoll for a number of seconds before McLain caught up to him.

Neither Thomas nor Thompson have dealt with this. Because they can't.

Edited June 29, 2023 by Pat Speer

[Michael Griffith]

15 hours ago, Pat Speer said:

Have you read my article on the photo evidence regarding the shooting? I hate to say it but Dale Myers is right. And McLain was telling the truth. He was not where the acoustics experts claimed he would have to have been at the time of the first shot. 

I was asked to provide my analysis to Tink and co. while his book was in preparation. I did so. Evidently they felt the best way to avoid the obvious was to not mention it. The films and photos prove McLain was not where they said he was. I will not dismiss the acoustics altogether because it could be that a different mic at a different location could record a similar impulse. But it certainly looks like the whole thing is junk science. I mean, the HSCA report used a still from the Dorman film to prove McLain was in the proper position, but that still was taken 20 or more seconds later. Don Thomas tried to counter this by moving the first shot to a later time. But his claims are equally problematic, as he has McLain traveling something like 4 mph across the plaza, hiding behind this car than that car etc, so there is no photo of him crawling across the plaza.

What we have instead is this... 

McLain is at far left. Note that Dave Wiegman is filming the Newmans. Well, when one studies the Wiegman film one realizes that this moment occurs towards the end of his film, so this is something like 30 seconds after the first shot. Now, the acoustics experts claimed the motorcycle traveled at a consistent speed across the Plaza--I believe they estimated 11 mph. This speed supposedly put McLain in the proper position to be in place for the sound signature of each sound on the recording. And yet here he is, just passing Wiegman, a cameraman who ran from a car after the first shot, a cameraman who has been on the knoll for a number of seconds. 

Now get this. The acoustics experts claimed they identified the location of Mclain's mic at the time of the first shot. And, golly, this location was roughly two cars ahead of Wingman's location at this time. So, yeah, to subscribe to the HSCA acoustics analysis means you believe Wiegman, carrying a heavy camera not only raced past McLain, who was riding a motorcycle, but passed him so rapidly he had time to film the scene on the knoll for a number of seconds before McLain caught up to him.

Neither Thomas nor Thompson have dealt with this. Because they can't.

I think it has been a while since you read Thomas's articles on this issue, especially his long reply to Dale Myers. Rather than recite all of Thomas's arguments against Myers and Bugliosi regarding McClain's position, I refer interested readers to these two links:

The Bike with the Mike        
https://www.maryferrell.org/pages/Essay_-_The_Bike_With_the_Mike.html

Debugging Bugliosi
https://www.maryferrell.org/pages/Essay_-_Debugging_Bugliosi.html

Thompson did not ignore your analysis. He did not agree with it. You may know that Thompson consulted closely with Don Thomas in writing his book. He concluded that Thomas had the better arguments regarding McClain. 

What do you have to say about the new tests that BBN conducted at Thompson's request? How about the two papers written by two BBN acoustical experts that are included in Thompson's book?

This statement of yours caught my attention:

I will not dismiss the acoustics altogether because it could be that a different mic at a different location could record a similar impulse.

If by "different location" you mean a location other than Dealey Plaza, this will not work because of the intricate echo-pattern matches between the gunshot impulses on the tape and the gunshot impulses from the field test in Dealey Plaza.

But, if you mean that a different motorcycle, i.e., other than McClain's, was in the locations identified by the acoustical analysis and thus recorded the impulses found on the tape, then at least you are not dismissing as mere coincidences all the remarkable acoustical correlations between the police tape, the windshield-distortion test done in New York, and the test firing done in Dealey Plaza.  

And I will beat this drum endlessly: Anyone who says that the identified gunshot impulse patterns on the tape are not gunfire and/or were not recorded during the assassination needs to explain, for starters, why those impulse patterns not only contain N-waves, muzzle blasts, and muzzle-blast echoes but contain them in the right order and interval, and why those impulse patterns contain windshield-distortion characteristics and contain them only when the motorcycle was in position to enable them to occur. 

Edited June 29, 2023 by Michael Griffith

[Pat Speer]

1 hour ago, Michael Griffith said:

I think it has been a while since you read Thomas's articles on this issue, especially his long reply to Dale Myers. Rather than recite all of Thomas's arguments against Myers and Bugliosi regarding McClain's position, I refer interested readers to these two links:

The Bike with the Mike        
https://www.maryferrell.org/pages/Essay_-_The_Bike_With_the_Mike.html

Debugging Bugliosi
https://www.maryferrell.org/pages/Essay_-_Debugging_Bugliosi.html

This statement of yours caught my attention:

I will not dismiss the acoustics altogether because it could be that a different mic at a different location could record a similar impulse.

If by "different location" you mean a location other than Dealey Plaza, this will not work because of the intricate echo-pattern matches between the gunshot impulses on the tape and the gunshot impulses from the field test in Dealey Plaza.

But, if you mean that a different motorcycle, i.e., other than McClain's, was in the locations identified by the acoustical analysis and thus recorded the impulses found on the tape, then at least you are not dismissing as mere coincidences all the remarkable acoustical correlations between the police tape, the windshield-distortion test done in New York, and the test firing done in Dealey Plaza.  

And I will beat this drum endlessly: Anyone who says that the identified gunshot impulse patterns on the tape are not gunfire and/or were not recorded during the assassination needs to explain, for starters, why those impulse patterns not only contain N-waves, muzzle blasts, and muzzle-blast echoes but contain them in the right order and interval, and why those impulse patterns contain windshield-distortion characteristics and contain them only when the motorcycle was in position to enable them to occur. 

As stated, my rejection of the McLain theory had been noted, and I was asked to provide arguments against it to help those working with Tink on his book, Last Second in Dallas. This was years after Thomas' last writings on the subject. I read all of Thomas' articles and found they only provided more reasons to doubt. I wrote an article on the subject to try and dissuade Tink from publishing what was essentially a thumbs up on the McLain theory. But, tellingly, the book focuses on shortcuts and mistakes by the Ramsey panel, etc, and spends very little time as I remember it arguing against anything I'd brought to Tink et al's attention. 

https://www.patspeer.com/debunking-the-dictabelt

Edited June 29, 2023 by Pat Speer

[Michael Griffith]

2 hours ago, Pat Speer said:

As stated, my rejection of the McLain theory had been noted, and I was asked to provide arguments against it to help those working with Tink on his book, Last Second in Dallas. This was years after Thomas' last writings on the subject. I read all of Thomas' articles and found they only provided more reasons to doubt. I wrote an article on the subject to try and dissuade Tink from publishing what was essentially a thumbs up on the McLain theory. But, tellingly, the book focuses on shortcuts and mistakes by the Ramsey panel, etc, and spends very little time as I remember it arguing against anything I'd brought to Tink et al's attention. 

https://www.patspeer.com/debunking-the-dictabelt

Well, this is another case where I just do not see what you say you see in photographic evidence, just as I do not see what you claim to see in the autopsy photos and x-rays and in Baden's demonstration regarding the clothing holes, to name a few examples. And in this case, we are not just talking about seeing this or that but about subjective judgments about how far X could have moved in Y time, about whether Photo A corresponds with Frame B in this or that footage, etc., etc.

More important, I would note that your article does not even mention, much less try to explain, the powerful evidentiary correlations that show that the tape contains gunfire recorded in Dealey Plaza:

The N-waves, the muzzle blasts, the muzzle-last echoes, and the fact that they occur at the right time and in the right order and interval; the windshield-distortion patterns, and the fact that they occur only when they could have occurred; the remarkable timing-movement correlations between the tape's gunshot impulses and the gunshot impulses from the Dallas test firing, which even the skeptical David Kaiser finds impressive and impossible to dismiss; and the fact that the tape's gunshot echo patterns match the echo-pattern fingerprint of Dealey Plaza. (Other evidence could also be cited.)

These correlations cannot be waved aside just because the incomplete photographic record does not enable us to identify the motorcycle with certainty. Simply put, critics of the acoustical evidence must answer this fundamental question: If the N-waves, muzzle blasts, muzzle-blast echoes, windshield distortions, and Dealey Plaza echo patterns on the tape were not recorded in Dealey Plaza during the assassination, how did they get on the tape?

Dismissing these correlations on the basis of an incomplete photographic record is not terribly far from being as untenable as saying that JFK could not have been shot in Dealey Plaza because no photo shows a gunman firing at JFK in the plaza, because the evidence strongly indicates that Oswald was eating lunch and getting a soda from 12:15-12:30, because no one saw a gunman firing from the grassy knoll or from any other spot in the plaza, and because the witnesses disagreed so markedly about the number and direction of the gunshot sounds that they may have merely been hearing motorcycle backfires.

Edited June 29, 2023 by Michael Griffith