Acoustic Evidence

[John Corbett]

Barber has proved no such thing. You are decades behind the information curve. You might want to read my last 10 replies in this thread to educate yourself on the acoustical evidence.

That wouldn't educate anybody but could give them quite a few chuckles.

[Tommy Shanks]

Barber has proved no such thing. You are decades behind the information curve. You might want to read my last 10 replies in this thread to educate yourself on the acoustical evidence.

No, you're a complete nutjob who believes every dumb JFK conspiracy theory. I'd love to see you explain exactly why Steve Barber didn't prove the Dictabelt did not record Dealey Plaza gunfire. I'd also love to see you explain which DPD officer was in Dealey Plaza during the murder who also had his mic stuck open. Won't hold my breath...

[John Corbett]

No, you're a complete nutjob who believes every dumb JFK conspiracy theory. I'd love to see you explain exactly why Steve Barber didn't prove the Dictabelt did not record Dealey Plaza gunfire. I'd also love to see you explain which DPD officer was in Dealey Plaza during the murder who also had his mic stuck open. Won't hold my breath...

This looks like the perfect time for an MTG diversion away from the topic being discussed.

[Michael T. Griffith]

After I first began to study the JFK case, I came across conspiracy theorist Harrison Edward Livingstone's rejection of the HSCA's acoustical evidence. When he cited the alleged Decker "hold everything" crosstalk, I didn't know enough to see any problem with it.

However, when Livingstone stressed that one of his reasons for rejecting the acoustical evidence was that the shots could not be heard with the naked ear on the dictabelt, my acoustical training led me too see a potential red flag. I knew that if the DPD radio system included Automatic Gain Control (AGC) circuitry, the AGC would have prevented the shots from being recorded loudly enough to be heard with the naked ear. 

This was my first hint that the case against the acoustical evidence might not be nearly as strong as "everyone" seemed to think it was.

However, I remained skeptical of the acoustical evidence until I obtained a copy of the HSCA volumes and read the testimony and reports of the committee's acoustical scientists.

When I later read the NRC/NAS panel's critique of the acoustical evidence, one of the first things I realized was that the panel did not even address several key items of evidence that the BBN and Queens College acoustical scientists had documented.

I was like, "Wait a minute. How can you guys claim to have refuted the acoustical evidence when you haven't even mentioned some of the key scientific findings that support it?" I was referring, of course, to the gunfire N-waves, complete with muzzle blasts and muzzle-blast echoes in the correct timing and order, and the gunfire windshield distortions on the dictabelt.

I also recognized that the panel had acknowledged that their own calculations showed there was a 93% probability that the timing-movement correlations identified by the BBN scientists occurred because the tape recorded gunfire in Dealey Plaza. I noticed that the panel made this admission as obliquely as possible and oddly said nothing about its obvious importance.

I further recognized that the panel had acknowledged that their own calculations showed there was a 77.7% probability that the dictabelt's 144.9 impulse pattern was caused by gunfire from the grassy knoll. Here, too, I noticed that the panel made this admission as obliquely as possible and said nothing about its obvious importance.

I thought, "Ok, 77.7% isn't as high as '95% or higher,' but it's still pretty high." This, of course, was before I learned that the panel's calculations included two outright errors, and that the "95% or higher" probability was actually closer to 99%.

I wondered how the panel could dismiss the acoustical evidence given these admissions and given their failure to address several key scientific findings that supported the acoustical evidence.

[Michael T. Griffith]

I recommend that everyone, especially newcomers to the acoustical evidence, read Jason Wakefield's March 2003 article "An In-Depth Study of the Acoustical Evidence in the JFK Assassination." Wakefield's article provides an excellent overview of the history of the acoustical evidence and where research on the dictabelt stood as of 2003.

In 2003, Linsker and his colleagues were still struggling to produce a response to Dr. Don Thomas's 2001 defense of the acoustical evidence in the forensic science journal Science & Justice. The Linsker group submitted a rebuttal to Thomas's article in March 2002 but quickly withdrew it. In reading the draft rebuttal, it is apparent why they withdrew it: it raised only minor points against Thomas's article. They spent three more years working on a response.

In this 2001 article, Dr. Thomas made a convincing case, based on the NRC/NAS panel's calculations for the timing of the transmissions on Channel 1 and Channel 2, that the Bellah "you want" transmission was a far more plausible timing indicator than the Decker "hold everything" transmission. In short, Dr. Thomas showed that if the NRC/NAS timing calculations were correct (and he assumed they were), the Bellah transmission was a far superior timing indicator than the Decker transmission, which refuted the NRC/NAS panel's main argument against the acoustical evidence.

It is crucial to understand that the primary scientific argument that the NRC/NAS panel made against the acoustical evidence was that the Decker "hold everything" transmission was crosstalk and that this proved the impulse patterns on the dictabelt were recorded about one minute after the shooting. Until the panel finally looked into Steve Barber's information about the Decker transmission, they had done nothing but manage to reduce the probability of the timing-movement correlations from 99+% to 93% and to reduce the probability of the grassy knoll shot from 95+% to 77.7% (and only by introducing two severe errors into their calculations).

It is even more crucial to understand that the Decker crosstalk hoax was based on the demonstrably false assumption that Channel 2 stopped recording for about 60 seconds. You don't need to be a scientist to understand that if Channel 2 had stopped recording for 60 seconds, the police dispatcher's subsequent time notations would reflect such a pause, but this did not happen. There is no time missing between the 12:30 and 12:32 transmissions, and the 12:35 and 12:36 time notations occur exactly five and six minutes respectively after the 12:30 time notation, proving, at least on this planet, that Channel 2 could not have stopped recording for 60 seconds (nor for 35 seconds). Dr. Thomas:

The linear regression analysis of the dispatcher's time notations proves that the Audograph machine must have shut off for extended times prior to the assassination. But after 12:30, the approximate time of the shooting, the dispatcher's announced times and the actual elapsed time fall into very close agreement for the six minutes after the shooting. There did not seem to be any appreciable amount of time missing, and none between 12:30 and 12:32 when the relevant broadcasts were made and where a full minute of time is supposed to be missing according to the NRC Panel. That is, there is exactly 120 seconds of playback time between the dispatcher's time notations at 12:30 and 12:32. . . .

Note for example (Table 15) that the dispatcher's time notation for 12:32 occurs exactly two minutes after the notation at 12:30. The NRC panel's theory holds that the recorder stopped for a half minute during this interval. It is indeed possible that the real interval between the time notations was actually two and a half minutes apart and by coincidence the lost 31 seconds only makes it appear that no time was lost. But if this were the case, one would expect to see an offset in the time notations downstream. But there is not. The 12:35 and 12:36 time notations fall exactly five and six minutes respectively after the 12:30 time notation, suggesting that the recording is continuous. . . . (Hear No Evil, 2010, pp. 638-639)     

So let us return to the Linsker group and Dr. Thomas's 2001 article. As mentioned, using the NRC/NAS panel's own timing calculations, Dr. Thomas showed that the Bellah "you want" transmission, which the panel acknowledged was crosstalk, was a far more probable timing indicator than the Decker "hold everything" transmission.

In order to refute Dr. Thomas's argument, Linsker and his colleagues had to make a painful admission when they finally submitted their rebuttal in 2005: they had to admit that the NRC/NAS panel's timing calculations were badly off the mark because they had miscalculated the needle-skip adjustment as 60 seconds when in fact it was 35 seconds.

But this was the poster child for a "ruinous victory," i.e., a victory that does fatal damage to the victor. Why? Because, in proving the Bellah crosstalk was not the best time indicator, Linsker and his colleagues were forced to admit that the only way the Decker "hold everything" transmission could be crosstalk was if Channel 2 stopped recording for 35 seconds. This version of the recording-pause theory faced the same unanswerable objection that the NRC/NAS version of the theory faced: a substantial pause on Channel 2, whether 60 seconds, or 44 seconds, or 35 seconds, would cause the dispatcher's subsequent time notations to reflect such a pause, but they do not.

Again, as many scholars have noted, the 12:35 and 12:36 time notations occur exactly five and six minutes respectively after the 12:30 time notation, and there is no time missing between the 12:30 and 12:32 broadcasts. How could this be if Channel 2 stopped recording for 35 seconds? Linsker et al. offered no explanation for why the alleged 35-second pause does not show up in the dispatcher's subsequent time notations. This is one of the facts that caught Dr. David Kaiser's attention and caused him to reject the attacks on the acoustical evidence.

And, as discussed in previous replies, subsequent research by BBN scientists from 2015-2019 has proved that the Decker transmission is an overdub and that the Fisher "I'll check" transmission is crosstalk, which proves that the dictabelt's impulse patterns were recorded during the assassination. Dr. Josiah Thompson discusses this historic new research at length in his book Last Second in Dallas. BBN scientists Dr. James Barger and Dr. Richard Mullen each wrote an appendix for the book.

Just bumping this thread as a reminder that LNers have failed to explain the gunfire windshield distortions on the dictabelt, the timing-movement correlations between the dictabelt's impulse patterns and the impulse patterns from the Dealey Plaza test firing, the 26-point match in the sonar analysis between the 144.9 impulse pattern and the grassy knoll test shot's impulse pattern, and the gunfire N-waves on the dictabelt, complete with muzzle blasts and muzzle-blast echoes that occur in the correct order and interval.

The only seemingly scientific argument that critics have made against the HSCA's acoustical evidence is the never-plausible, debunked Decker crosstalk argument, which relied from the outset on the impossible theory that Channel 2 stopped recording for at least 35 seconds and for as many as 60 seconds. As discussed in the quoted reply, this theory is impossible because no such recording pause is reflected in the subsequent six minutes of the tape; the 12:35 and 12:36 time notations occur exactly five and six minutes respectively after the 12:30 time notation, and there is no time missing between the 12:30 and 12:32 broadcasts.

Allow me to again provide the link to my article "The HSCA's Acoustical Evidence: Proof of a Second Gunman."

[Tommy Shanks]

When is Michael T. Griffith going to identify the motorcycle officer whose mic was stuck open to record the gunfire in Dealey Plaza during the assassination? Surely he is aware that it could not possibly have been H.B. McLain. So then who was it?