|JFK Assassination Records|
|Oswald interviews, and acoustic studies relating to the assassination of JFK.|
|DPD Acoustic Studies|
|In November 1963, when President John F. Kennedy was assassinated, the Dallas Police Department recorded police radio traffic onto Dictabelt and Audograph devices. In 1978 the US House of Representatives authorized a new investigation into the Kennedy Assassination. That investigation concluded by finding a probable conspiracy, based on the evidence of those police recordings.
Bolt Beranek and Newman (BBN), a firm with expertise in acoustic studies, was hired to analyze the police recordings. The hope was that one of the police vehicles in the presidential motorcade might have captured the sound of gunfire, and could provide information about the shots fired.
BBN reported to the House that they had detected signals in the noisy recording that were probably caused by gunfire, and that using echo-location techniques to determine the source of shots, there was a 50% probability of a shot from the grassy knoll.
BBN Acoustics Report to HSCA
The House committee then contracted a couple of experts from Queen's College to refine this inconclusive result. Mark Weiss and Ernest Aschkenasy (W&A) used another technique to analyze the head shot and concluded with a 95% probability that there was a shot from the grassy knoll.
Weiss and Aschkenasy Acoustics Report to HSCA
Based primarily on this study the House Committee said there was a conspiracy.
HSCA Finding on acoustics.
Completing its task, the House turned the case over to the Justice Department for possible further action. The FBI disputed the acoustic studies. In the fall of 1980 the Justice Department requested that the National Research Council (NRC) review the issue. The NRC formed a committee of prominent scientists, the Committee on Ballistic Acoustics (CBA).
In 1982 the CBA published an article in the journal "Science" and a full report through the National Academy of Sciences (NAS). In these reports they documented an instance of "crosstalk", reported to them by Steve Barber, in which sounds from one police channel were picked up on the other channel. This instance contained indentifiable speech from after the shooting and overlayed the signals that BBN and W&A thought were gunshots. This demonstrated that the signals couldn't have really been shots because they happened too late.
Steve Barber wrote an essay about his experience.
After the CBA report, Dr. James Barger, lead scientist on the BBN team, wrote a letter to the lead investigator of the HSCA suggesting further work that might be done.
A member of the CBA, Dr. Richard Garwin, and some of his associates at IBM authored a follow-up to the CBA report, delving into some technical issues on the recordings.
In 2001 an independent scientist, Dr. Don Thomas, published an article in the British forensics journal, "Science & Justice". This article cited statistical errors by the CBA and a conflicting instance of "crosstalk" that showed the signals tagged as gunshots could have happened at the correct time.
Don Thomas article (Science and Justice)
When this article was published this author (Michael O'Dell) began reviewing the previous work. I was fortunate to run into Johann Rush, who provided me with old tape copies of the police recordings. Meanwhile, some former members of the CBA decided to revisit the issue and work on a response to the Thomas article. Steve Barber put me in touch with them and they provided me with digital copies of the recordings from the files of the CBA.
The Acoustic Evidence in the Kennedy Assassination by Michael O'Dell
The former CBA members along with Dr. Ralph Linsker of IBM, published their article in "Science & Justice" in 2005.
Linsker, Garwin, Chernoff, Horowitz, Ramsey Article in Science & Justice
Both my article, and the Linsker et al article, showed that the original CBA timeline of events on the recordings were in error, and when this error was corrected the alternative timing proposed by Thomas was no longer possible.