The HSCA Acoustical Evidence: Proof of a Second Gunman in the JFK Assassination

[Michael T. Griffith]

You bring up so many low-quality arguments that I don’t bother to respond to most of them.

LOL! "Low-quality arguments"?! You mean like when you made the comical claim that the HSCA acoustical experts found N-waves "scattered throughout" the dictabelt tape? You mean like when you made erroneous claims about what was and was not done in the preliminary analysis because you clearly did not know the basic timeline of the HSCA acoustical analysis, did not know what was done in the preliminary analysis vs. what was done later? You mean like when you gave the wrong time that the HSCA acoustical experts gave for when the first shot occurred (because you were relying on Bowles' bogus transcript)? You mean like when you spent weeks making the false claim that the 4-second impulse pattern was rejected only because it was too short, when in fact it was rejected because it failed two--not just one--of the initial screening tests and showed no N-wave or muzzle-blast patterns? You mean like when you somehow, someway mistook Barger's testimony for the BBN report? You mean like when you initially pretended that windshield distortion is not a known phenomenon in acoustical science? And on and on I could go.

You have proved yourself to be a total joke on the acoustical evidence. But, every time you are caught in an egregious gaffe, you brush it off and post more endlessly long replies based on your misreading and/or mischaracterization of the HSCA materials. You never quote any scholars. You run to pro-WC propaganda sites and often copy and paste their bogus arguments but present them as your own. 

My "low-quality arguments" are based on the research done by the only six acoustical experts to ever analyze the dictabelt tape (Barger, Robinson, Schmidt, Wolf, Weiss, Aschkenasy), by an internationally recognized expert in shock physics (Chambers), by a scholar with a PhD in mathematics from MIT (Scheim), by a research scientist whose work on the acoustical evidence has been published in a peer-reviewed criminal science journal (Thomas), by a scientist with a degree in mathematics and another degree in applied mathematics (Charnin), by a physicist who's authored books on physics and astronomy (Stahl), among other scholars. And I have quoted from most of these scientists' analyses.

Well, I could deal with this windshield-distortion issue the same way Dr. Barger deals with these sorts of problems. The windshield-distortion correlations should be considered “false alarms”, that is “false positives”, so I don’t have to account for them.

This is too ignorant, too comical to waste time answering. But, I will duly add this claim to your ever-growing list of howlers.

The fact that the BBN found correlations, for 3 of the 5 shots, for both the TSBD and the Grassy Knoll, outweigh any consideration of windshield-distortion. What is windshield-distortion compared to misestimating the position of the shooter, with some of the correlations by over 200 feet.

This is more raw, comical ignorance. 200 feet?! This goofiness is based on your continued misreading of the HSCA materials. You realize that nearly instantaneous echoes caused some of the individual matches but that these were recognized as false positives by time-distance analysis of the motorcycle's movements, right? You realize that any rational doubt about the grassy-knoll-shot matches was removed by the WA sonar analysis, right?

But now, on to handling the windshield-distortion issue. You claim that windshield-distortion did occur with the first three shots from the TSBD (I assume 137.70, 139.27 and 140.32) but did not occur with the Grassy Knoll shot at 145.15. Now, the question I have, is:

Who determined this?

I don’t recall reading where Dr. Barger or any report from BBN discussed this windshield-distortion in their reports to the HSCA.

And it couldn’t have been Weiss and Aschkenasy because, as I understand it, they only looked at the grassy knoll shot of 145.15. They did not look at the earlier shots at all, because of a lack of time. So, they might have said there was no windshield-distortion for the grassy knoll shot, but they couldn’t have had an opinion on the 3 earlier shots.

So, I would guess it would be our Insect expert, Dr. Thomas, who determined, from his analysis, that the first three shots had no windshield-distortion, but the grassy knoll shot did.

Question:

Is this right? The determination of the first 3 shots had windshield-distortion, but the grassy knoll shot did not, was not made by Dr. Barger. Was not made by BBN. Was not made by Weiss and Aschkenasy, but was instead made by Dr. Thomas?

It appears to me, that the source of this “No Windshield-Distortion” for the grassy knoll shot is: Jason A. Perdue

In his book:

People in High Places – An Investigation of the Assassination of President John F. Kennedy

So "it couldn’t have been Weiss and Aschkenasy," hey? Weiss and Aschkenasy could not have discussed the windshield-distortion evidence, hey? This gaffe proves you still have not bothered to read their testimony. Dr. Weiss talked about windshield distortion extensively in his testimony. He explained how windshield distortion accounted for some of the patterns seen in the graphical representation (oscillogram/spectrogram) of the dictabelt gunshot impulse patterns:

The second thing is, if you look at these patterns in somewhat more expanded detail than perhaps is visible here, you will see in the case of the muzzle blast there is a very sharp, short, initial, positive, upward going spike or peak, then it goes strongly down, and then it comes up again, and so on.

Now, in fact, as recorded through a high-fidelity system and an open microphone, it really does this, it is very sharply upward first, then it goes down and so on.

Well, something must have happened to this upward, strong one to make it seem much smaller. It now is just a little bitty one over here. It goes down, and now it comes up afterwards, and does that sort of thing. And we considered why that is so, and thought that it is probable that if this is a microphone on the motorcycle, and the motorcycle, in fact, is over here in Dealey Plaza, facing in this direction, and if there is a rifle over here, that the windshield of the motorcycle is sort of between the sound that comes directly at it from the muzzle blast and the microphone, so the windshield is screening the microphone to some degree.

Well, the effect of that can be predicted. But to confirm our understanding of this, we arranged with the New York City Police Department to perform some experiments at their shooting range in the Bronx. We went out there, and they trotted out an old Harley-Davidson motorcycle and put a transmitter on it, vintage 1963 or 1964, and an old microphone pretty much the same kind as was used by the Dallas Police Department, and we performed some experiments with people firing rifles at various locations, sometimes with the motorcycle facing the shooter, sometimes with the motorcycle crosswise to the shooter. At the same time we made recordings using high fidelity equipment of the sounds of the shots.

Now there were two kinds of recordings made. The first, as I say, was high fidelity equipment, good microphone, good recorder on the spot. The second was through the microphone which was on the motorbike, which was a microphone of the type used in Dallas, through the transmitter, and recorded downtown at the police communications laboratory. And we compared the results of these two recordings, and what we found was exactly what we had thought we would find, that is, that in the case of the high fidelity recording, we got that kind of big, first spike upward and downward, and so on. In the case of the recording made through the police microphone, that first spike was greatly attenuated [weakened] and it went negative and came back up and so on. This was true, however, only in the case where the motorcycle was facing the rifle.

When the motorcycle was crosswise to the rifle, the recording made by the police microphone fairly closely matched, looks, looked pretty much like, with some distortions, but looked pretty much like the recording made using the high fidelity equipment. So it was essentially confirmed that the windshield really does have this effect on reducing the strength of that initial, very sharp spike received, and, of course, this is what we have over here. It is consistent with the assumption that this is a microphone behind the windshield facing a rifle. (5 HSCA 581-582)

[Joe Elliott]

And I see Mr. Elliott has apparently decided to stop trying to deal directly with the windshield-distortion correlations and is once again demanding answers to his irrelevant, error-based questions. Just to recap, the three TSBD shots contain windshield distortion because the patrolman's microphone was in a position where the gunshot sound waves would have encountered his windshield before reaching the microphone. But, for the grassy knoll shot, where the motorcycle was in a position where the windshield did not intervene between the gunshot sound waves and the microphone, there is no windshield distortion. Think about the number of factors that would have to come together to make these correlations possible. Here are just some of them:

It now appears that it is Mr. Griffith who is running away from the windshield-distortion correlation issue. So, let me repeat the point I made yesterday.


The grassy knoll shot was the fourth of the five shots (if one accepts the 140.32 as a shot).

The following map shows where the motorcycle was for this shot, the fourth green circle.




Questions:

1.   Shouldn’t we expect to have windshield-distortion from the grassy knoll for this shot?

2.   What do you mean that the windshield would not intervene with the grassy knoll shot?

Of course, it would have. The motorcycle would have been almost pointed directly at the grassy knoll, while in the fourth circle.

[Michael T. Griffith]

Mr. Elliott's surprising claim that the windshield-distortion correlations originated with Jason Perdue's book People in High Places deserves further comment. Anyone who has read the HSCA materials knows that not only did Weiss and Aschkenasy note these correlations in their testimony and in their report, but that the HSCA report noted them as well.

But now, on to handling the windshield-distortion issue. You claim that windshield-distortion did occur with the first three shots from the TSBD (I assume 137.70, 139.27 and 140.32) but did not occur with the Grassy Knoll shot at 145.15. Now, the question I have, is:

Who determined this?

I don’t recall reading where Dr. Barger or any report from BBN discussed this windshield-distortion in their reports to the HSCA.

And it couldn’t have been Weiss and Aschkenasy because, as I understand it, they only looked at the grassy knoll shot of 145.15. They did not look at the earlier shots at all, because of a lack of time. So, they might have said there was no windshield-distortion for the grassy knoll shot, but they couldn’t have had an opinion on the 3 earlier shots.

So, I would guess it would be our Insect expert, Dr. Thomas, who determined, from his analysis, that the first three shots had no windshield-distortion, but the grassy knoll shot did.

Question:

Is this right? The determination of the first 3 shots had windshield-distortion, but the grassy knoll shot did not, was not made by Dr. Barger. Was not made by BBN. Was not made by Weiss and Aschkenasy, but was instead made by Dr. Thomas?

It appears to me, that the source of this “No Windshield-Distortion” for the grassy knoll shot is: Jason A. Perdue

In his book:

People in High Places – An Investigation of the Assassination of President John F. Kennedy

I had never heard of Perdue's book until I read this reply. I tracked down an online copy of the book (2nd edition). Perdue does not say the grassy knoll shot had no windshield distortion. He correctly observes that the final shot was the one that was found to have no windshield distortion, not the grassy knoll shot (pp. 69-70).

Coincidentally, just before I looked up Perdue's book, I realized that the fourth shot was the no-windshield-distortion shot after I went back and re-read the HSCA report's section on the acoustical evidence. I have revised my article on the acoustical evidence accordingly.

When you look at the position of the motorcycle for the third shot and the fourth shot, it makes perfect sense that the fourth shot does not contain any windshield distortion. For the grassy knoll shot, as with the two previous shots, the windshield was still between the rifle and the microphone, but this was not the case for the fourth shot. This is an astonishing coincidence if the dictabelt tape does not contain JFK assassination gunfire.

Several folks who have read Weiss's testimony on this subject have inferred that he was implying that the grassy knoll shot was the shot with no windshield distortion. This is how I had read his testimony as well. This is even how Dr. Chambers read his testimony. With tongue in cheek, I blame Dr. Weiss for not specifying by number the shots with windshield distortion ala the HSCA report! The HSCA report sets the matter straight:

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.(55) 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)

So, now that we have cleared up the confusion about which shots were and were not found to contain windshield distortion, we see that the windshield-distortion correlations are powerful, convincing evidence that the police tape contains at least four gunshots. Again, if these correlations are all just a coincidence, they are an astounding, astronomically improbable coincidence. When you think about the number of factors that would have to align by pure chance to make it theoretically possible for these correlations to be mere coincidence, you realize that the only rational conclusion is that they are not a coincidence but are hard evidence that the HSCA acoustical experts were correct.

[Joe Elliott]

Mr. Elliott's surprising claim that the windshield-distortion correlations originated with Jason Perdue's book People in High Places deserves further comment. Anyone who has read the HSCA materials knows that not only did Weiss and Aschkenasy note these correlations in their testimony and in their report, but that the HSCA report noted them as well.

I had never heard of Perdue's book until I read this reply. I tracked down an online copy of the book (2nd edition). Perdue does not say the grassy knoll shot had no windshield distortion. He correctly observes that the final shot was the one that was found to have no windshield distortion, not the grassy knoll shot (pp. 69-70).

Coincidentally, just before I looked up Perdue's book, I realized that the fourth shot was the no-windshield-distortion shot after I went back and re-read the HSCA report's section on the acoustical evidence. I have revised my article on the acoustical evidence accordingly.

When you look at the position of the motorcycle for the third shot and the fourth shot, it makes perfect sense that the fourth shot does not contain any windshield distortion. For the grassy knoll shot, as with the two previous shots, the windshield was still between the rifle and the microphone, but this was not the case for the fourth shot. This is an astonishing coincidence if the dictabelt tape does not contain JFK assassination gunfire.

Several folks who have read Weiss's testimony on this subject have inferred that he was implying that the grassy knoll shot was the shot with no windshield distortion. This is how I had read his testimony as well. This is even how Dr. Chambers read his testimony. With tongue in cheek, I blame Dr. Weiss for not specifying by number the shots with windshield distortion ala the HSCA report! The HSCA report sets the matter straight:

So, now that we have cleared up the confusion about which shots were and were not found to contain windshield distortion, we see that the windshield-distortion correlations are powerful, convincing evidence that the police tape contains at least four gunshots. Again, if these correlations are all just a coincidence, they are an astounding, astronomically improbable coincidence. When you think about the number of factors that would have to align by pure chance to make it theoretically possible for these correlations to be mere coincidence, you realize that the only rational conclusion is that they are not a coincidence but are hard evidence that the HSCA acoustical experts were correct.

I did make an error. I found a phrase you quoted from an unnamed source, did a google search, and found it in a book published by Jason Perdue’s book, “People in High Places”. So, you were not quoting Jason Perdue. You were both quoting an HSCA report. But this was not clear from your original post.

Coincidentally, just before I looked up Perdue's book, I realized that the fourth shot was the no-windshield-distortion shot after I went back and re-read the HSCA report's section on the acoustical evidence. I have revised my article on the acoustical evidence accordingly.

https://www.archives.gov/research/jfk/select-committee-report/part-1b.html

And here is the paragraph from Weiss and Aschkenasy. It straddles Page 73 and 74:

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.11 On shot four, Weiss and Aschkenasy found no such distortion. (55) 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.

So, yes, the shot that that Weiss and Aschkenasy found no windshield distortion was the four BBN shot, or the fifth Thomas shot, the last shot. And it was determined to be from the TSBD.

I’m still a little perplexed about this though. Yes, the windshield would not be in the way of this last shot. But Officer McLain’s torso would have been squarely in the way. So, I am not too impressed with Weiss and Aschkenasy finding no distortion in this last impulse, as they had found in the first three. Why wouldn’t Officer McLain’s torso cause distortions, when the sound waves were forced to bend around his torso, just as the wound waves had to bend around the windshield from the first three shots.

Several folks who have read Weiss's testimony on this subject have inferred that he was implying that the grassy knoll shot was the shot with no windshield distortion. This is how I had read his testimony as well. This is even how Dr. Chambers read his testimony. With tongue in cheek, I blame Dr. Weiss for not specifying by number the shots with windshield distortion ala the HSCA report! The HSCA report sets the matter straight:

How could Dr. Chambers be ignorant of all this?
How could he not know that for the “grassy knoll” shot, the grassy knoll would be almost directly ahead of the motorcycle?
How could Dr. Chambers have concluded that the Weiss and Aschkenasy found no windshield distortion for the grassy knoll shot?

I thought Dr. Chambers was supposed to be a big expert on the acoustics of this case. It sounds like he doesn’t even know the basics. For you or me to make such an error is understandable. Not for Dr. Chambers.

And by the way, I don’t see anything in Dr. Weiss’s testimony that implies the grassy knoll shot would have no windshield distortion. So, I don’t see how Dr. Chambers got that idea, either from the testimony nor from the final report.

Question:
How did Dr. Chambers make two such large errors?
1.   Believed the grassy knoll would be off to the side of the motorcycle when it recorded the next to last shot.
2.   Believed that Weiss and Aschkenasy found no windshield distortion with the grassy knoll shot.

I see nothing obvious in the testimony or the final report that could lead to such errors.

[Jerry Freeman]

How exactly would a stuck microphone confuse the activities in Dealey Plaza?

DUH...communication breakdown just at the exact time of the shooting. Another remarkable coincidence huh?

[Joe Elliott]

When I first heard the police tapes...I came to the conclusion that the "stuck microphone" was a deliberate act to confuse the activities in Dealey Plaza. I still think so.

How exactly would a stuck microphone confuse the activities in Dealey Plaza?

DUH...communication breakdown just at the exact time of the shooting. Another remarkable coincidence huh?

Yes, but my question stands What practicable effect do you think a “stuck microphone” to have?

Do you imagine that without a stuck microphone, the Dispatcher would immediately direct these two policemen to this spot, those two policemen to that spot, maximizing the odds of catching someone? No, the only practicable effect is that without a stuck microphone, the Dispatcher could send in other units to Dealey Plaza immediately to help with the search. But even with an immediate response, it will take many minutes for units to arrive from other parts of Dallas. In the meantime, any shooter can leave the area, even if only moving at a walking pace.

With or without a stuck microphone, either the policemen already at Dealey Plaza are going to, on their own, in the first ten minutes, catch a shooter, or they are not. The radio network, the Dispatcher, policemen who are elsewhere, aren’t going to make a difference in the immediate search.

As it was, what effect did the stuck microphone have on the search? None. Officers, acting without instructions, went looking for the shooter. Officer Baker went into the building and climbed the stairs, on his own initiative. He did not need the Dispatcher to tell him what to do. If the microphone was not stuck, he still would not call in for instructions. That takes too much time and ties up the radio for everyone else. In a situation like this, everyone has to do what they think is best. Any coordination is going to have to come from senior officers already on the spot. Not from the radio network.


And these communication breakdowns, a stuck microphone key, was hardly an unknown event and was always plaguing the police department.

[Michael T. Griffith]

I’m still a little perplexed about this though. Yes, the windshield would not be in the way of this last shot. But Officer McLain’s torso would have been squarely in the way. So, I am not too impressed with Weiss and Aschkenasy finding no distortion in this last impulse, as they had found in the first three. Why wouldn’t Officer McLain’s torso cause distortions, when the sound waves were forced to bend around his torso, just as the wound waves had to bend around the windshield from the first three shots.

This won't work. The sound waves would have been coming from high above McClain and at a lateral angle from this right. At most, some of the waves might have encountered a portion of the top part of his right shoulder, resulting in minimal distortion, if any.

But the HSCA acoustical experts tested for windshield distortion and found that it significantly weakened the recorded sounds, by 3-6 decibels, when the windshield was between the rifle and the microphone (8 HSCA 31). They also found that shots received from the sides and rear were not affected by the windshield:

Obviously, sounds received from the sides and rear of the motorcycle would not be affected by the windshield. (8 HSCA 31)

Just the fact that the first three shots all contain windshield distortion is an amazing correlation. The fact that the fourth shot shows no such distortion is equally remarkable. The four correlations combined constitute powerful evidence that the dictabelt tape recorded assassination gunfire.

How could Dr. Chambers be ignorant of all this?
How could he not know that for the “grassy knoll” shot, the grassy knoll would be almost directly ahead of the motorcycle?
How could Dr. Chambers have concluded that the Weiss and Aschkenasy found no windshield distortion for the grassy knoll shot?

I thought Dr. Chambers was supposed to be a big expert on the acoustics of this case. It sounds like he doesn’t even know the basics. For you or me to make such an error is understandable. Not for Dr. Chambers.

And by the way, I don’t see anything in Dr. Weiss’s testimony that implies the grassy knoll shot would have no windshield distortion. So, I don’t see how Dr. Chambers got that idea, either from the testimony nor from the final report.

Question:
How did Dr. Chambers make two such large errors?
1.   Believed the grassy knoll would be off to the side of the motorcycle when it recorded the next to last shot.
2.   Believed that Weiss and Aschkenasy found no windshield distortion with the grassy knoll shot.

I see nothing obvious in the testimony or the final report that could lead to such errors.

Well, hold on now. Let's be fair and accurate about this. Dr. Chambers was correct in saying that the HSCA experts found windshield distortions in the shots that should have contained them and did not find such distortions in the shot that should not have contained them. That, after all, is the main point. He simply misidentified which shot does not contain windshield distortion. It's an error, to be sure, but it does not affect the main point. So it's not like this is some horrendous gaffe.

But, yes, even very good experts with exceptional qualifications make a mistake every now and then.

Dr. Chambers' chapter on the acoustical evidence is far superior to Sturdivan's errant and misleading chapter on the subject.