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

[Michael T. Griffith]

The BBN started with the noblest of intentions and ended as a farce.

It was thought, that analyzing the Dictabelt tape, they could deduce:

1.   The position of the shooter.
2.   The position of where the shot was aimed at, that is, where it stuck.
3.   The position of the motorcycle with the stuck microphone.

Going into this, I sure Dr. Barger had hopes of getting excellent data. And if this excellent data showed the motorcycle was elsewhere, or was at Dealey Plaza but recorded three shots from the TSBD, that would be a disappointment. But, if he discovered multiple firing locations, it would be the greatest scientific crime discovery of the century. I am certain his hopes were up.

So, they ran some firing tests in Dealey Plaza on August 27, 1978, and recorded the shots on 36 microphones arranged along Houston and Elm Street.

Below is a simplified version of BBN’s Exhibit F-367, which shows the correlations that they discovered.

Test	Beginning Time of	Zap.	Rifle	Target
ID	First impulse on	Frame	Location	Location
	Tape Segments (sec)	(Thomas)
A	136.20
B	137.70	176	TSBD	Location-z 155
D	137.70	176	TSBD	Location-z 313
E	137.70	176	KNOLL	Location- Tague
G	139.27	205	TSBD	Location-z 313
I	139.27	205	TSBD	Location-z 313
J	139.27	205	KNOLL	Location-z 313
K	140.32	224	TSBD	Location-z 313
L	145.15	313	KNOLL	Location-z 313
M	145.15	313	TSBD	Location-z 224
N	145.15	313	TSBD	Location-z 313
O	145.61	321	TSBD	Location-z 313
P	145.61	321	TSBD	Location- Tague
Q	145.61	321	TSBD	Location-z 224
R	146.30

The “Zap. Frames” are Dr. Thomas’s estimate, not the original BBN estimate. They don’t differ by enough to make much of a difference so to avoid confusion, I just went with Dr. Thomas’s time estimate.

On this table, I don’t differentiate between the rifle in the TSBD being 2 feet behind the plane of the window, or sticking out further. It didn’t seem to make a lot of difference in the firing tests. So, I just consider these shots to be from the TSBD.

In the August 27, 1978 firing tests, they fired at four locations. Target 1, 2, 3 and 4.
Target 1 is about where the limousine was at the location shown in Zapruder frame z155.
Target 2 is about where the limousine was at the location shown in Zapruder frame z224.
Target 3 is about where the limousine was at the location shown in Zapruder frame z313.
Target 4 is about Mr. Tague was standing, about 240 feet beyond the z313 location.
So instead of listing the “Target Location” as “3”, I give it as “Location-z 313”.

So, how did they do?

1.   The position of the shooter.

Terrible.
Shot 1 at z176 - They got correlations found for both the TSBD and the Grassy Knoll. There should have only been a correlation for one location. One of these results must be bad. The degree of correlation was not high enough,
Shot 2 at z205 – Again, bad, correlations found for both the TSBD and the Grassy Knoll.
Shot 3 at z224 – One correlation for a shot from the TSBD. Getting just one correlation is actually good. It’s too bad they didn’t get this for all 5 shots.
Shot 4 at z304 – Again, bad, correlations found for both the TSBD and the Grassy Knoll.
Shot 5 at z313 – Correlations only for a shot from the TSBD. This is a good result.

2.   The position of where the shot was aimed at, that is, where it stuck.
Shot 1 at z176 – the shot struck at:
Location-z 155 – miss by 19 feet.
Location-z 313 – miss by 132 feet.
Location- Tague – miss by 272 feet.

Shot 2 at z205 – the shot struck at:
Location-z 313 – miss by 92 feet.

Shot 3 at z224 – the shot struck at:
Location-z 313 – miss by 75 feet.

Shot 4 at z304 – the shot struck at:
Location-z 224 – miss by 70 feet.
Location-z 313 – a hit on the limousine

Shot 5 at z313 – the shot struck at:
Location-z 224 – miss by 75 feet.
Location-z 313 – a hit on the limousine
Location- Tague – miss by 240 feet.

One the whole, terrible. The data contradicts itself. Clearly false correlations are more common than true.

Dr. Barger doesn’t seem the least bit phase. When the results contradict themselves, we should just assume we got some “false alarms”. We should just ignore the ones that don’t make sense and consider the ones that do reliable. These “false alarms” are a serious problem. They are more properly known as “false positives”. So many false positives in the data, where false positives are more common then true positives, bring all the true positives into doubt.

And if we follow Dr. Barger, throw out all the “false alarms”, what proposed shots have good support:

Shot 1 – at z152 – good support (a miss by 19 feet is good enough), if the two false positives are ignored.
Shot 2 – at z205 – no support, all correlations give unbelievable “Target location” that is off by 92 feet.
Shot 3 – at z224 – no support, the correlation gives unbelievable “Target location” that is off by 75 feet.
Shot 4 – at z304 – good support, if the two false positives are ignored.
Shot 5 – at z313 – good support, if the two false positives are ignored.

Two of the five “found” shots, strictly speaking, should be thrown out, because misses by 70 feet or more is just too unbelievable.

3.   The position of the motorcycle with the stuck microphone.

Here we have much better correlations. These correlations are what Mr. Griffith really likes to emphasis.

The data is consistent with a motorcycle traveling at around 11 mph, trailing behind the limousine by 120 to 160 feet. Which should plausible. But there is a problem with the film evidence. The Hughes film shows the only possible officer, Officer McLain, along with his partner, Officer Baker, trailing behind the limousine by 300 feet. By the time the film shuts off, Officer McLain has 1.5 seconds to cover 170 feet, impossible. Also, he should appear in the Altgens photograph.

But let’s ignore all that. We still, seemingly, have a remarkable correlation with the data and a plausible set of positions of the motorcycle. What are we to make of this data as a whole? Random looking correlations for the position of the shooter and the area of the street the bullets struck. Good correlation for the position of the motorcycle. This is truly hot ice and wondrous strange snow.

But there is a simple explanation. For a through check of all possible correlations:
432 strip charts from the 1978 firing tests, 36 microphones times 12 test shots
Need to be each compared with the 6 possible shots from the 1963 Dictabelt recording.
So, 2,592 comparisons need to be made between pairs of strip charts for the 1978 tests and the 1963 recording.

This sounds difficult to do in 15 days, to get done in time to present the data to the HSCA. They have to:

Decide which of the 1978 78 test shots are to be compared, they selected 12 of them.
Print out 12 strip charts for them.
Print out 432 strip charts for the 1978 data.
Make all 2,592 comparisons, which involve counting waves within a certain number of milliseconds and doing some calculations to get a “correlation coefficient”
Organize all the data and print them out in a neat form to present to the HSCA.

I would suggest that maybe they did not perform all 2,592 combinations of comparisons. From one shot, it seemed the motorcycle was 150 feet behind. With the time limit, it made sense to only search for where the motorcycle might be. Why search the data from a stretch of street that you probably wouldn’t find a motorcycle. And if a correlation was found about where expected, 150 feet behind, under the time pressure, it’s time to move on to the next shot.

If something like this happened, all the correlations found would be consistent with a motorcycle averaging 11 mph, 120 to 160 feet behind the limousine. Even if a through processing of the entire data set may have found many contradictions on the location of the motorcycle, just as was found with the location of the shooter and the location of the target.

Until proven otherwise, I hold that this is the most likely scenario that explains this “hot ice and wondrous strange snow” results.

Dr. Barger’s fundamental error, is that he allowed his hopes to affect his judgement. These “false alarms”, should have set off a real alarm in his head. It should have been apparent to him that he was measuring “noise”, garbage data that contradicted itself which was what data is that contains too many false positives. This work will be his legacy, it will overshadow everything else he was done in his career.

Just about every single statement in your reply is either false, irrelevant, or based on a misreading/misrepresentation of the HSCA materials due to your ignorance on the subject. You've already admitted that you refuse to read Dr. Thomas's book, and it's clear that you still have not read the BBN report (if you have, one wonders how on earth you could say the things you say). How about Dr. Chambers' chapter on the acoustical evidence?

Let's just take your last paragraph, the one about false alarms. BBN and WA developed very reliable tests to distinguish between the false alarms and the gunshot impulse patterns to a degree of certainty of well over 95%. Dr. Weiss explained to one congressman who asked him if the third and fourth gunshot impulses could be "acoustical mirages" of one shot that this was impossible because the third shot--the grassy knoll shot--contained specific echo-pattern characteristics of a test-firing shot from the grassy knoll, because each echo has "its own peculiar distortion, transmission characteristics":

Mr. WEISS. No, sir; because in order for that to be true, you would have to, in effect, have had the sound of the muzzle blast transported by some means to the
location of the grassy knoll area, and there emitted as if it had originated from that point. Since every echo that was predicted corresponded to an echo arising from a sound rising from that location [in the test firing], what you would have required is that echoes otherwise generated from a shot fired, say, from the depository window, would each have had its own peculiar distortion, transmission characteristics such that by some marvelous process it occurred at the microphone, intact, and at the correct position. (5 HSCA 608)

People who understand the acoustical evidence will realize that you are still just posting paragraphs of diversionary smoke and are still avoiding the powerful, intricate correlations between the dictabelt shots and the test-firing shots. If all those gunshot impulses are merely false alarms, then you need to explain the correlations, unless you're merely going to argue that they are all amazing, staggering coincidences.

You can't explain the correlations because there is no Web article that deals with those correlations, and so you have no source from which to copy and paste to address them. That's why you keep avoiding them.

How about if you just explain one of the correlations in the acoustical evidence: the windshield-distortion correlations? The HSCA scientists realized that soundwaves passing through a motorcycle windshield would experience distortion. So they ran tests to determine the characteristics of windshield distortion. And, lo and behold, they found that the dictabelt shots that match test shots from the Book Depository all contained windshield distortions but that the dictabelt shot that match test shots from the grassy knoll contain no such distortions. My, my, my!

Try to fathom the odds that three out of four dictabelt gunshot impulses would just happen to contain windshield distortions in the first place, and then try to fathom the odds that the one gunshot impulse that should not contain those distortions would not contain them.

He has gone from being a respected scientist to having an insect expert as his main ally.

This petty, juvenile, and erroneous comment shows why you are not credible, why you are not to be taken seriously. First of all, all of the BBN acoustical scientists stood behind the acoustical evidence, not just Dr. Barger. So did Weiss and Aschkenasy. Second, your continued harping on the fact that Dr. Thomas is an entomologist ignores the fact that he is also an expert in statistics, and that Dr. Chambers, a world-renowned physicist, and Dr. Scheim, a graduate of MIT in mathematics, also support the acoustical evidence. You don't mind citing a urologist on ballistics and forensic issues, but you object when an entomologist is cited on the acoustical evidence, even though his acoustical research has been praised by Dr. Barger and other scientists.

[Joe Elliott]

Question 1:

In the BBN Exhibit F-367 Table, a portion of which I show here:

Test	Beginning Time of	Zap.	Rifle	Target
ID	First impulse on	Frame	Location	Location
	Tape Segments (sec)	(Thomas)
B	137.70	176	TSBD	Location-z 155
D	137.70	176	TSBD	Location-z 313
E	137.70	176	KNOLL	Location- Tague

Why does it show the impulse pattern at 137.70 as matching the patterns expected by shots from both the TSBD and the Grassy Knoll?


It seems to me, that at least 2 of these matches are by luck. They are flukes. And this is the explanation for 2 of the matches, why not all 3?

How about if you just explain one of the correlations in the acoustical evidence: the windshield-distortion correlations? The HSCA scientists realized that soundwaves passing through a motorcycle windshield would experience distortion. So they ran tests to determine the characteristics of windshield distortion. And, lo and behold, they found that the dictabelt shots that match test shots from the Book Depository all contained windshield distortions but that the dictabelt shot that match test shots from the grassy knoll contain no such distortions. My, my, my!

The common pattern you show, is when you cannot answer my questions, you introduce another argument from left field. So instead of dealing with the contradictions in the BBN’s own data, you bring up “windshield-distortion”.

The shots from the TSBD contain windshield-distortions but those from the grassy knoll do not?

How can anyone say that when the BBN data, for the shots at z176, z205 and z313, match the pattern predicted for both a shot from the TSBD and the grassy knoll?

Question 2:

Did the impulse patterns correspond to z176, z205 and z213 shots, show “windshield-distortions”?

This petty, juvenile, and erroneous comment shows why you are not credible,

You are constantly insulting me with every post you direct to me. I don’t do that to you. You write like a 5-year-old who is constantly having a temper tantrum. I am just asking for clarifications for why the BBN data, the Exhibit F-367 Table, appears to contradict itself so much. And you are not explaining why, either to me or the other readers.

[Michael T. Griffith]

The common pattern you show, is when you cannot answer my questions, you introduce another argument from left field.

No, you ask me ridiculous, diversionary, irrelevant questions, and I attempt to get you to address the real issues, the same issues that the NRC panel and O'Dell and Bowles have never gotten around to addressing: the remarkable, intricate correlations between the dictabelt gunshot impulse patterns and the test-firing impulse patterns.

I have commented on your confusion about F-367 in several replies, including one very long reply where I quoted extensively from Dr. Barger's testimony where he explained F-367. But you keep ignoring what he said and keep demanding that your imagined "contradictions" be "explained."

So instead of dealing with the contradictions in the BBN’s own data,

The "contradictions" are in your mind, or else you know better but are hoping you'll fool others.

you bring up “windshield-distortion”.

Uh, yeah, because windshield distortion is a known factor in acoustical analysis, because we know from science that when soundwaves pass through a windshield, the windshield causes certain distortions in the wave and in the echo pattern. You'd know that if you had bothered to do your homework.

The shots from the TSBD contain windshield-distortions but those from the grassy knoll do not? How can anyone say that when the BBN data, for the shots at z176, z205 and z313, match the pattern predicted for both a shot from the TSBD and the grassy knoll?

How could the HSCA experts say that the TSBD shots contain windshield distortion? Because they ran tests on this to determine the patterns that would be caused by windshield distortion. From the WA report:

A different but also significant effect on the relative strengths of the recorded echoes would have been caused by the motorcycle windshield. On the DPD motorcycles, the microphone was usually mounted on a bar directly behind the windshield. Sounds arriving from the front of the motorcycle would have diffracted around the windshield and in doing so would have lost strength. As determined by experiment, the windshield of a 1960's Harley Davidson motorcycle attenuated [weakened] gunshot sounds received from in front of the motorcycle by 3 decibels to 6 decibels. The amount of attenuation [weakening, decreasing] depended on how close the microphone was to the windshield. Obviously, sounds received from the sides and rear of the motorcycle would not be affected by the windshield. (8 HSCA 30-31)

Then, when the HSCA scientists did the refined analysis, they found that the TSBD shots all contain windshield distortion but that the grassy knoll shot goes not. Dr. G. Paul Chambers, a renowned physicist who has worked with NASA, the Naval Surface Warfare Center, and the Naval Research Laboratory:

Weiss and Aschkenasy . . . also took into account muting and distortion of the acoustical signature due to the windshield of the motorcycle. When they considered this in their analysis, they found that the earlier shots determined by BBN to be from the Texas School Book Depository showed this distortion, while the acoustical sequence that matched the test shot from the grassy knoll did not exhibit this effect.

This is precisely the result expected for a microphone mounted on a motorcycle moving in Kennedy’s motorcade along Houston Street facing the Depository, where the sound of the shot from this location would pass through the windshield, but moving sideways to the direction of the grassy knoll so that a shot from this location would not need to pass through the windshield to reach the microphone. This lent further credence to the validity of their analysis. (Chambers, Head Shot: The Science Behind the JFK Assassination, p. 102)

Question 2:

Did the impulse patterns correspond to z176, z205 and z213 shots, show “windshield-distortions”?

This is a silly, disingenuous question. And I see you again put "windshield-distortions" in quotes, as if windshield distortion is not a known, scientifically established phenomenon.

You are constantly insulting me with every post you direct to me. I don’t do that to you. You write like a 5-year-old who is constantly having a temper tantrum.

You repeatedly insult and belittle Dr. Thomas, calling him "a bug guy," "an insect guy," etc., but you get upset when I call you out for making ignorant claims. I am just tired of your dishonesty, your evasion, and your misrepresentation. You have done nothing but duck and dodge and bob and weave every time I have asked you direct, clear questions about the dictabelt-test firing correlations.

I am just asking for clarifications for why the BBN data, the Exhibit F-367 Table, appears to contradict itself so much.

No you're not. You're throwing up a bunch of absurd smoke to avoid dealing with the core of the acoustical evidence. And I'm just not going to waste time playing your games. Again, I have already dealt at length with your misreading/misrepresentation of F-367.

And you are not explaining why, either to me or the other readers.

Oh, I'll let our readers decide whether or not I am "explaining why." Your silly questions are answered by the HSCA materials and in subsequent research. Your questions are based either on a surreal misreading of the HSCA materials or on a deliberate misrepresentation of them.

The HSCA scientists explained in detail how they separated the false alarms/false positives from the final candidate impulses. They explained how they screened every single impulse on the dictabelt tape. They explained how they compared the viable candidate impulse patterns to patterns of test-firing gunshots. They explained how they identified N-waves, muzzle blasts, and muzzle-blast echoes. They explained how they tested for windshield distortion. They explained how they matched the test-firing echo patterns to the gunshot impulse patterns on the dictabelt tape. Etc., etc. etc.

But you don't want to talk about any of that. You keep bringing up ancillary issues based on your misreading/misrepresentation of the HSCA materials, most of which you have not even really read. And you have defiantly announced that you will not read the most authoritative analysis of the acoustical evidence now available, i.e., Dr. Thomas's four chapters on the subject in his book Hear No Evil, even though he wrote them in close consultation with Dr. Barger.

[Joe Elliott]

In the BBN Exhibit F-367 Table, a portion of which I show here:

Test	Beginning Time of	Zap.	Rifle	Target
ID	First impulse on	Frame	Location	Location
	Tape Segments (sec)	(Thomas)
B	137.70	176	TSBD	Location-z 155
D	137.70	176	TSBD	Location-z 313
E	137.70	176	KNOLL	Location- Tague

Question 1:

Why do the impulses from three different 1978 test shots, resemble each other so closely, even though the shots are from fired from two different locations, at three different targets separated from each other by over a hundred feet?

So close that the BBN found a correlation with each of these three-test shot with the 1963 Dictabelt impulse of 137.70.


Question 2:

Shouldn’t each test shot, fired from different positions and/or fired at widely separate targets, produce its own unique wave pattern that would not be shared with other test shots?


Question 3:

How can the science of Acoustics be used to reconstruct what happened when a recorded impulse pattern correlation with different firing positions, firing at different targets?

It would seem impossible to say that “this shot was fired from this position, firing at this target”, because of Correlation “A” when Correlation “B” contradicts this.

[Joe Elliott]

********** Warning, this is not the real data, only what good data should look like **********

Test	Beginning Time of	Zap.	Rifle	Target
ID	First impulse on	Frame	Location	Location
	Tape Segments (sec)	(Thomas)
B	137.70	176	TSBD	Location-z 155
G	139.27	205	TSBD	Location-z 224
K	140.32	224	TSBD	Location-z 224
L	145.15	313	KNOLL	Location-z 313
O	145.61	321	TSBD	Location-z 313

********** Here is the data the BBN actually got **********

Test	Beginning Time of	Zap.	Rifle	Target
ID	First impulse on	Frame	Location	Location
	Tape Segments (sec)	(Thomas)
A	136.20
B	137.70	176	TSBD	Location-z 155
D	137.70	176	TSBD	Location-z 313
E	137.70	176	KNOLL	Location- Tague
G	139.27	205	TSBD	Location-z 313
I	139.27	205	TSBD	Location-z 313
J	139.27	205	KNOLL	Location-z 313
K	140.32	224	TSBD	Location-z 313
L	145.15	313	KNOLL	Location-z 313
M	145.15	313	TSBD	Location-z 224
N	145.15	313	TSBD	Location-z 313
O	145.61	321	TSBD	Location-z 313
P	145.61	321	TSBD	Location- Tague
Q	145.61	321	TSBD	Location-z 224

Question:

Why didn’t the data the BBN end up looking something like the first table. Where we don’t have contradictory correlations. Like a 1963 Dictabelt impulse pattern matches both a shot from the TSBD and from the Grassy Knoll. Where the shots end up hitting on or at least reasonably near the limousine?

Instead, we end up with a chart that contradicts itself, shows support for the same shot coming from the TSBD and the Grassy Knoll. And as far as “Target Locations” seems to find random correlations, and not correlations where the target location matches the limousine location at that time.

Why is that?



The obvious answer is bad data. And using a correlation coefficient threshold that is too low. Giving us random answers as to the location of the shooter and the location of the target.



The only part of the data is the location of the motorcycle. Well, not that good, because it does not match what is in the Hughes film and the Altgens photograph. But this can be explained by the hypotheses that the BBN only checked for matches where they anticipated where the motorcycle might be. Not all possible combinations but only the ones that seemed plausible. Due to a lack of time. So, if they found the first match 150 feet behind the limousine, they would look for the second 150 feet behind the limousine at the time of the second “shot”. So whatever correlation they discovered, it would match a motorcycle travelling 150 feet behind the limousine at around 11 mph.

Hence, the poor correlation of the location of the shooter, the poor correlation of the location of the target, but the good correlation of the location of the motorcycle. To me, this explanation makes sense.

[Michael T. Griffith]

********** Warning, this is not the real data, only what good data should look like **********

Test	Beginning Time of	Zap.	Rifle	Target
ID	First impulse on	Frame	Location	Location
	Tape Segments (sec)	(Thomas)
B	137.70	176	TSBD	Location-z 155
G	139.27	205	TSBD	Location-z 224
K	140.32	224	TSBD	Location-z 224
L	145.15	313	KNOLL	Location-z 313
O	145.61	321	TSBD	Location-z 313

********** Here is the data the BBN actually got **********

Test	Beginning Time of	Zap.	Rifle	Target
ID	First impulse on	Frame	Location	Location
	Tape Segments (sec)	(Thomas)
A	136.20
B	137.70	176	TSBD	Location-z 155
D	137.70	176	TSBD	Location-z 313
E	137.70	176	KNOLL	Location- Tague
G	139.27	205	TSBD	Location-z 313
I	139.27	205	TSBD	Location-z 313
J	139.27	205	KNOLL	Location-z 313
K	140.32	224	TSBD	Location-z 313
L	145.15	313	KNOLL	Location-z 313
M	145.15	313	TSBD	Location-z 224
N	145.15	313	TSBD	Location-z 313
O	145.61	321	TSBD	Location-z 313
P	145.61	321	TSBD	Location- Tague
Q	145.61	321	TSBD	Location-z 224

Question:

Why didn’t the data the BBN end up looking something like the first table. Where we don’t have contradictory correlations. Like a 1963 Dictabelt impulse pattern matches both a shot from the TSBD and from the Grassy Knoll. Where the shots end up hitting on or at least reasonably near the limousine?

Instead, we end up with a chart that contradicts itself, shows support for the same shot coming from the TSBD and the Grassy Knoll. And as far as “Target Locations” seems to find random correlations, and not correlations where the target location matches the limousine location at that time.

Why is that?

The obvious answer is bad data. And using a correlation coefficient threshold that is too low. Giving us random answers as to the location of the shooter and the location of the target.

The only part of the data is the location of the motorcycle. Well, not that good, because it does not match what is in the Hughes film and the Altgens photograph. But this can be explained by the hypotheses that the BBN only checked for matches where they anticipated where the motorcycle might be. Not all possible combinations but only the ones that seemed plausible. Due to a lack of time. So, if they found the first match 150 feet behind the limousine, they would look for the second 150 feet behind the limousine at the time of the second “shot”. So whatever correlation they discovered, it would match a motorcycle travelling 150 feet behind the limousine at around 11 mph.

Hence, the poor correlation of the location of the shooter, the poor correlation of the location of the target, but the good correlation of the location of the motorcycle. To me, this explanation makes sense.

This is both comical and pathetic.  These questions are based on a mix of misreading and/or misrepresentation and omission.

Plus, I have already debunked several of the claims in his reply, but Mr. Elliott keeps repeating them anyway: To cite just one example, regarding his claim that "BBN only checked for matches where they anticipated where the motorcycle might be," this is utterly erroneous and is the exact opposite of what they did. It is beyond me how anyone could get on a public board and make such an abjectly false statement when the relevant materials make it clear that the BBN scientists did the exact opposite of what Mr. Elliott claims they did.

Be advised that Mr. Elliott is the same guy who spent weeks claiming that the 4-second impulse pattern was rejected only because it wasn't long enough, who could not tell the difference between Barger's testimony and the BBN report, who did not even understand the basic timeline of the HSCA acoustical analysis (i.e., the preliminary analysis vs. the later analysis done after the test firing), who did not even know when the HSCA said the first shot was fired, among other egregious errors. I don't mention these things to kick a wounded horse, but just to enable readers to understand Mr. Elliott's record of making erroneous statements.

The best way to answer Mr. Elliott's ball of confusion is not to spend numerous paragraphs unpacking his errors and omissions but to provide a clear explanation of the relevant facts. I will do so by quoting from Dr. G. Paul Chambers' chapter on the acoustical evidence in his book Head Shot: The Science Behind the JFK Assassination.

Dr. Chambers is a physicist and an internationally recognized expert in the field of shock physics. He has performed extensive high-speed photographic studies of high-velocity impacts and deformations of solids as well as computer modeling of shock wave and matter interactions. He has worked with NASA at NASA's Goddard Optics Branch. He has worked as a supervisory research physicist at the Energetic Materials and Detonation Science Department of the Naval Surface Warfare Center, and as a research physicist with the Condensed Matter and Radiation Sciences Division of the Naval Research Laboratory. The quote below appears in my article on the acoustical evidence, the same article that Mr. Elliott keeps pretending to be answering:

The HSCA commissioned the acoustics firm of Bolt, Beranek, & Newman (BBN) to perform a scientific analysis on the Dictabelt recording. This firm had previously successfully utilized acoustical analysis to determine the events that transpired during the Kent State shooting in 1970. Their acoustical analysis was later used as evidence presented to a grand jury to determine which national guardsman had fired first. BBN was also pointed by Judge John J. Sirica to serve on a panel of technical experts to analyze President Richard Nixon’s Watergate tapes.

Led by their chief scientist, Dr. James Barger, BBN converted the sounds on the tapes [the Channel 1 tape and the Channel 2 tape] to digitized waveforms. They then ran the waveforms through electronic filters to eliminate repetitive background noise like the sound of the motorcycle pistons firing. The firm then examined the processed waveforms for “sequences of impulses.” Their analysis indicated that there were six sequences of interest, spaced together within an eleven-second period recorded on channel 1, which could be consistent with the sounds of gunshots. . . .

Weiss and Aschkenasy reviewed Barger’s analysis and conclusions. They found that Barger’s analysis was valid and his conclusions supported by the evidence on the tape. They concurred with his recommendation to conduct live-fire tests in Dealey Plaza to determine the origin and direction of the gunshots, and they approved his plan for acoustical reconstruction. . . .

In Dealey Plaza, the sounds of gunshots would produce similar echoes. When recorded and captured on a specialized electronic device like an oscilloscope that converts sound patterns into pictures, these echoes appear as “acoustical waveforms” and appear as unique signatures of sound-producing events. In the case of a rifle shot in Dealey Plaza, the acoustical signatures would differ based on the origin, direction, and velocity of the shot, as well as the location of the recording microphone. The echo patterns would depend on the timing of sound reflections off building or other structures and obstructions in the plaza. . . .

A recording was made of the sounds received at each microphone during each test shot, making a total of 432 recordings of impulse sequences. . . . Each recorded impulse sequence was then compared with each of the six impulse patterns on the channel 1 Dictabelt recording to see the degree to which significant points in each impulse pattern matched. . . .

The time of the arrival of the impulses, or echoes, in each sequence of impulses was the characteristic being compared, not the shape, amplitude, or any other characteristic of the impulses or sequences. . . .

When the BBN team performed their analysis of the acoustical waveforms, they
found something extraordinary. When they compared the impulse sequences
from the acoustical reconstruction to the sequences on the original Dictabelt
recording, they found a number of significant matches. When the locations of the
microphones that recorded matches in the reconstruction were plotted on a
graph of time versus distance, it was found that the location of the microphones
that recorded matches were clustered around a line on the graph that was
consistent with the known speed of the motorcade (11 mph). . . .

Of the thirty-six microphones placed along the motorcade route, the one that recorded the sequence of impulses that matched the third impulse on the 1963 dispatch tape [the dictabelt tape] was farther along the route than the one that recorded the impulses that matched the second impulse on the dispatch tape. The locations of the microphones were consistent with the distance a motorcycle traveling at about 11 mph would cover in the elapsed time between impulses on the dispatch tape. . . . Applying a statistical formula, Barger estimated that since the microphones clustered around a line representing the speed of the motorcade, there was a 99 percent probability that the Dallas police dispatch tape did, in fact, contain impulses transmitted by a microphone in the motorcade in Dealey Plaza during the assassination. . . .

Weiss and Aschkenasy, specialists in sonar applications . . . examined Dealey Plaza carefully to determine which structures were most likely to have caused the echoes recorded by the microphone in the acoustical reconstruction that had exhibited a match to the shot from the grassy knoll. They verified and refined their identifications of echo-producing structures by examining the results of the 1978 reconstruction [the test firing in Dealey Plaza]. This approach allowed them to look for matches in the data with a 1 ms [millisecond] correlation. . . . Matches at this level of temporal precision substantially reduced the possibility that a
match could occur as a result of random noise.

In Dealey Plaza, echoes from gunshot test patterns arrive in two discrete [different] clusters, differing in time by about 190 ms. Echoes originating from structures along Elm Street arrive within 85 ms, while echoes from structures farther back on Houston Street arrive in the last 95 ms of a typical 370-msduration test pattern. In addition, a “muzzle blast” is usually prominent at the beginning of a gunshot acoustical pattern, while an N-wave (a shock wave traveling faster than the speed of sound due to the rifle bullet exceeding the sound barrier) arrives prior to the muzzle blast. The waveform identified as the grassy knoll shot is shown in figure 13. The presence of an N-wave in this waveform was consistent with the acoustical signature of a supersonic rifle bullet.  . . .

Weiss and Aschkenasy were able to incorporate the movement of the motorcycle in their analytical model. For instance, over the time period of the 370-ms gunshot acoustical pattern recording, the motorcycle would have moved about five feet. Therefore, corrections had to be made to account for a moving microphone during the actual 1963 events. They also took into account muting and distortion of the acoustical signature due to the windshield of the motorcycle. When they considered this in their analysis, they found that the earlier shots determined by BBN to be from the Texas School Book Depository showed this distortion, while the acoustical sequence that matched the test shot from the grassy knoll did not exhibit this effect.

This is precisely the result expected for a microphone mounted on a motorcycle moving in Kennedy’s motorcade along Houston Street facing the Depository, where the sound of the shot from this location would pass through the windshield, but moving sideways to the direction of the grassy knoll so that a shot from this location would not need to pass through the windshield to reach the microphone. This lent further credence to the validity of their analysis. (Chambers 96-102)

Here is my article, the one that Mr. Elliott keeps pretending he's answering:

https://miketgriffith.com/files/hscaacous.pdf

[Joe Elliott]

This is both comical and pathetic.  These questions are based on a mix of misreading and/or misrepresentation and omission.

Plus, I have already debunked several of the claims in his reply, but Mr. Elliott keeps repeating them anyway: To cite just one example, regarding his claim that "BBN only checked for matches where they anticipated where the motorcycle might be," this is utterly erroneous and is the exact opposite of what they did. It is beyond me how anyone could get on a public board and make such an abjectly false statement when the relevant materials make it clear that the BBN scientists did the exact opposite of what Mr. Elliott claims they did.

Be advised that Mr. Elliott is the same guy who spent weeks claiming that the 4-second impulse pattern was rejected only because it wasn't long enough, who could not tell the difference between Barger's testimony and the BBN report, who did not even understand the basic timeline of the HSCA acoustical analysis (i.e., the preliminary analysis vs. the later analysis done after the test firing), who did not even know when the HSCA said the first shot was fired, among other egregious errors. I don't mention these things to kick a wounded horse, but just to enable readers to understand Mr. Elliott's record of making erroneous statements.

The best way to answer Mr. Elliott's ball of confusion is not to spend numerous paragraphs unpacking his errors and omissions but to provide a clear explanation of the relevant facts. I will do so by quoting from Dr. G. Paul Chambers' chapter on the acoustical evidence in his book Head Shot: The Science Behind the JFK Assassination.

Dr. Chambers is a physicist and an internationally recognized expert in the field of shock physics. He has performed extensive high-speed photographic studies of high-velocity impacts and deformations of solids as well as computer modeling of shock wave and matter interactions. He has worked with NASA at NASA's Goddard Optics Branch. He has worked as a supervisory research physicist at the Energetic Materials and Detonation Science Department of the Naval Surface Warfare Center, and as a research physicist with the Condensed Matter and Radiation Sciences Division of the Naval Research Laboratory. The quote below appears in my article on the acoustical evidence, the same article that Mr. Elliott keeps pretending to be answering:

Here is my article, the one that Mr. Elliott keeps pretending he's answering:

https://miketgriffith.com/files/hscaacous.pdf

Mr. Griffith is playing the same trick he often plays. He claims an issue has already been dealt with and provides a link to a long article. And implies that the answer is to be found somewhere in this article.

It would be easy for him to cut and paste the relevant paragraph if, it existed. As an example, I will cut and paste a random paragraph from his article to show how easy this is:


Random Paragraph:

Led by their chief scientist, Dr. James Barger, BBN converted the sounds on the
tapes [the Channel 1 tape and the Channel 2 tape] to digitized waveforms. They
then ran the waveforms through electronic filters to eliminate repetitive
background noise like the sound of the motorcycle pistons firing. The firm then
examined the processed waveforms for “sequences of impulses.” Their analysis
indicated that there were six sequences of interest, spaced together within an
eleven-second period recorded on channel 1, which could be consistent with the
sounds of gunshots. . . .

So as far as the two claims I have made, he has not really provided any quotes from Mr. Barger that either is false. These claims are:

1.   There are two impulse pattern sequences recorded, just during the 5.5-minute period that the transmission key is stuck. One is 10 seconds long, the other 4. So, it appears the 10-second-long sequence is not unique. Since both were not caused by gunfire, perhaps neither were.
Perhaps if this second sequence was analyzed, they would have found correspondence with some impulse waves from their 1978 tests.
The only quotes I can find from Dr. Barger, about why the 4-second sequence was not investigated further were:
a.   The sequence was too short, since the Zapruder film seemed to show the shooting lasted at least 5 seconds.
b.   He claims it must have been created by someone else trying to transmit over Channel 1. But does not provide any technical reasons why he believes this, like the amplitude of the waves was too large or too small. For all I know, this is speculation on Dr. Barger’s part.

2.   I believe it is likely that BBN did not systematically check all 2,592 combinations of the 432 waveforms, created in the 1978 tests, with the 6 waveforms of interest, recorded on the 1963 Dictabelt. I believe this was not done because of the lack of time, only 10 days to make the measurements and to do the calculations with calculators where all the numbers would have to be manually entered.
Instead, I speculate that after they thought they found one shot, they used this information, combined with the assumption that the motorcycle maintained a roughly 11 mph speed to tell them where to go look for other matches. If this was done, any correlation they found would match the scenario of a motorcycle moving at 11 mph. This would explain why the location of the motorcycle gets consistent results, which is what you want. While still getting random results for the location of the shooter and the area of Elm Street the bullet struck.
Again, this is speculation on my part but reasonable speculation. It provides an explanation as to why the data for the location of the motorcycle is good, while the data for the location of the shooter and where the bullet struck is so bad.
And Mr. Griffith, for all his bluster, has not provided us with a quote from Dr. Barger where he claims they did indeed conduct a systematic check of all possible 2,592 combinations in the time period of 10 days, from when the shooting tests were conducted, to when he called the HSCA to report that they had found 15 correlations.
Now, I can find claims on the internet that Dr. Barger had completed these 2,592 comparisons. But neither I, nor apparently Mr. Griffith, can find a where Dr. Barger claims that all these 2,592 comparisons were actually done.

Again, why should my speculation:
          that the BBN did not conduct a thorough systematic search through all 2,592 combinations, due to a lack of time
be considered more likely than Mr. Griffith’s speculation:
          that that BBN did conduct a thorough systematic search through all 2,592 combination, despite the time pressure

Because my theory explains why the BBN data is so bad at getting results that don’t contradict themselves as to the location of the shooter and where the bullet struck, while giving consistent results on the location of the motorcycle. And Mr. Griffith’s theory, does not.