John F. Kennedy assassination Dictabelt recording

A Dictabelt recording from a motorcycle police officer's radio microphone stuck in the open position became a key piece of evidence cited by the House Select Committee on Assassinations (HSCA) in their conclusion that there was a conspiracy behind the assassination of John F. Kennedy on November 22, 1963. Made on a common Dictaphone-brand dictation machine that recorded sound in grooves pressed into a thin vinyl-plastic belt, the recording gained prominence among Kennedy assassination conspiracy theorists following the HSCA's 1978 conclusion, based in part on this evidence, that there was a "high probability" that Lee Harvey Oswald did not act alone and that the Kennedy assassination was the result of a conspiracy.

John F. Kennedy

The recording was made from Dallas Police Radio Channel 1, which carried routine police radio traffic; Channel 2 was reserved for special events, such as the presidential motorcade. The open-microphone portion of the recording lasts 5.5 minutes, and begins at about 12:29 p.m. local time, a minute before the assassination.^{[1][2][3][4][5]} Verbal time stamps were made periodically by the police radio dispatcher and can be heard on the recording.^[6]

House Select Committee on Assassinations

In December 1978, the House Select Committee on Assassinations (HSCA) had prepared a draft of its final report, concluding that Lee Harvey Oswald had acted alone in the assassination. However, after evidence from the Dictabelt recording was made available, the HSCA quickly reversed its conclusion and declared that a second gunman had fired the third of four shots heard. In a January 5, 1980, interview with journalist Earl Golz, HSCA chief counsel G. Robert Blakey later said: "If the acoustics come out that we made a mistake somewhere, I think that would end it [the multiple-shooter theory]."^[7] Despite serious criticism of the scientific evidence and the HSCA's conclusions, speculation regarding both the Dictabelt and the possibility of a second gunman persisted.

Investigators compared "impulse patterns" (suspected gunshots and associated echos) on the Dictabelt to 1978 test recordings of Carcano rifles fired in Dealey Plaza from the sixth floor of the Texas School Book Depository and from a stockade fence on the grassy knoll forward and to the right of the location of the presidential limousine. On this basis, the acoustics firm of Bolt, Beranek and Newman (BBN) concluded that impulse patterns 1, 2, and 4 were shots fired from the Depository, and that there was a 50% chance that impulse pattern 3 was a shot fired from the grassy knoll. Acoustics analysts Mark Weiss and Ernest Aschkenasy of Queens College reviewed the BBN data and concluded that "with the probability of 95% or better, there was indeed a shot fired from the grassy knoll."^{[8][failed verification]}

Dr. James E. Barger of BBN testified to the HSCA that his statistical analysis of the impulse patterns captured on the Dallas police recordings showed that the motorcycle with the open microphone was about "120 to 138 feet" behind the presidential limousine at the time the first shot was fired.^[9] When the HSCA asked Weiss about the location of the motorcycle with the open microphone—"Would you consider that to be an essential ingredient in the ultimate conclusion of your analysis?"— Weiss answered, "It is an essential component of it, because, if you do not put the motorcycle in the place that it is —the initial point of where it was receiving the [sound of the gunfire]—, and if you do not move it at the velocity at which it is being moved on paper in this re-creation, you do not get a good, tight pattern that compares very well with the observed impulses on the police tape recording."^[10]

Using an amateur film shot of the motorcade,^[11] the HSCA concluded that the recording originated from the motorcycle of police officer H. B. McLain, who later testified before the committee that his microphone was usually stuck in the open position. McLain did not hear the actual recording until after his testimony, and upon hearing it, he adamantly denied that the recording came from his motorcycle. He said that the other sounds on the recording did not match any of his movements.^[12]

Sirens are not heard on the recording until over two minutes after what is supposed to be the sound of the shooting, even though McLain accompanied the motorcade to Parkland Hospital immediately after the shooting with sirens blaring the whole time. When the sirens are heard on the Dictabelt recording, they rise and recede in pitch (i.e., the Doppler effect) and volume, as if they are passing by. McLain also said that the engine sound was clearly from a three-wheeled motorcycle, not the two-wheeler that he drove. "There's no comparison to the two sounds," he said.^[13]

Other audio discrepancies also exist. Crowd noise is not heard on the Dictabelt recording, despite the sounds generated from the many onlookers along Dallas's Main Street and in Dealey Plaza (crowd noises can be heard on at least ten channel-2 transmissions from the motorcade). Someone is heard whistling a tune about a minute after the assassination.^[14] No one actually heard gunshots on the recording.^{[clarification needed][15][16]}

The only evidence that HSCA had for a second shooter was the Dictabelt sound recording.^[17][18][19] Four of the twelve HSCA members dissented to the HSCA's conclusion of conspiracy based on the acoustic findings, and a fifth thought a further study of the acoustic evidence was "necessary".^[20] Dissenting members of the committee included Congressmen Samuel L. Devine, Robert W. Edgar, and Harold S. Sawyer.^[21] Responding to a question asking how he would handle the Committee's report if he were at the Justice Department, Sawyer replied: "I'd file it in a circular file." ^[21][22]

Criticism

Richard E. Sprague, an expert on photographic evidence of the assassination and a consultant to the HSCA, noted that the amateur film the HSCA relied on showed that there was no motorcycle between those riding alongside the rear of the presidential limousine and H.B. McLain's motorcycle, and that other films^{[23][failed verification]} showed McLain's motorcycle was actually 250 feet behind the presidential limousine when the first shot was fired, not 120 to 138 feet. There was also no motorcycle anywhere near the target area.^[24]

Adult magazine Gallery published a pull-out laminated cardboard recording, like those on the back of Cereal boxes, of the Dictabelt recording in its July 1979 issue.^[25] Assassination researcher Steve Barber repeatedly listened to that recording and heard the words "Hold everything secure until the homicide and other investigators can get there" at the point where the HSCA had concluded the assassination shots were recorded.^[3] However, those words were spoken by Sheriff Bill Decker about 90 seconds after the assassination, so the shots could not be when the HSCA claimed.^[26]

The FBI's Technical Services Division studied the acoustical data and issued a report on December 1, 1980 (dated November 19, 1980). The FBI report concluded that the HSCA failed to prove that there were gunshots on the recording and also failed to prove that the recording was made in Dealey Plaza. In fact, using the techniques of the previous investigators, the FBI matched a gunshot recorded in Greensboro, NC in 1979 with the sound that was supposedly a shot from the grassy knoll – purportedly suggesting that the initial investigation's methods were invalid.^[27]

National Academy of Sciences

After the FBI disputed the validity of the acoustic evidence, the Justice Department paid for a review by the National Academy of Sciences, an organization operating with a Title 36 congressional charter.

On May 14, 1982, the panel of experts chaired by Harvard University's Norman Ramsey, released the results of their study.^[28] The NAS panel unanimously concluded that:

The acoustic analyses do not demonstrate that there was a grassy knoll shot, and in particular there is no acoustic basis for the claim of 95% probability of such a shot.
The acoustic impulses attributed to gunshots were recorded about one minute after the President had been shot and the motorcade had been instructed to go to the hospital.
Therefore, reliable acoustic data do not support a conclusion that there was a second gunman."^[29]

According to Ramsey, noises on the Dictabelt were "probably static".^[30] Louis Stokes, a member of the United States House of Representatives who chaired the HSCA, commented that the report "raised new and serious questions about our conclusions that need to be resolved."^[28]

Dr. Barger, the HSCA's acoustics expert, when asked about this discovery and the NAS analysis, replied,

Barber discovered a very weak spoken phrase on the DPD Dictabelt recording that is heard at about the time of the sound impulses we concluded were probably caused by the fourth shot. The NAS Committee has shown to our satisfaction that this phrase has the same origin as the same phrase heard also on the Audograph recording.^[31] The Audograph recording was originally made from the channel 2 radio. The common phrase is heard on channel 2 about a minute after the assassination would appear, from the context, to have taken place. Therefore, it would seem . . . that the sounds that we connected with gunfire were made about a minute after the assassination shots were fired. Upon reading the NAS report, we did a brief analysis of the Audograph dub that was made by the NAS Committee and loaned to us by them. We found some enigmatic features of this recording that occur at about the time that individuals react to the assassination. Therefore, we have doubt about the time synchronization of events on that recording, and so we doubt that the Barber hypothesis is proven. The NAS Committee did not examine the several items of evidence that corroborated our original findings, so that we still agree with the House Select Committee on Assassinations conclusion that our findings were corroborated^[32]

An analysis published in the March 2001 issue of Science & Justice by Dr. Donald B. Thomas used a different radio transmission synchronization to put forth the claim that the National Academy of Sciences panel was in error. Thomas' conclusion, very similar to the HSCA conclusion, was that the gunshot impulses were real to a 96.3% certainty. Thomas presented additional details and support in the November 2001 and September and November 2002 issues.^[33][34][35] Commenting on Thomas's study, G. Robert Blakey said: "This is an honest, careful scientific examination of everything we did, with all the appropriate statistical checks."^[36]

In 2005, Thomas' conclusions were rebutted in the same journal. Ralph Linsker and several members of the original NAS team, (Richard Garwin, Herman Chernoff, Paul Horowitz, and Ramsey) reanalyzed the timings of the recordings and reaffirmed in an article in Science & Justice the earlier conclusion of the NAS report that the alleged shot sounds were recorded approximately one minute after the assassination.^[37]

Further analysis

The United States Department of Justice reviewed the HSCA report and the National Academy of Science's study of the sound evidence. It reported to the Judiciary Committee on March 28, 1988, and rebuked the HSCA's conclusion of a probable conspiracy.^[38]

In 2003, an independent researcher named Michael O'Dell reported that both the National Academy and Dr. Thomas had used incorrect timelines because they assumed the Dictabelt ran continuously. When corrected, these showed the impulses happened too late to be the real shots even with Thomas's alternative synchronization. He pointed out that the claim of a 95% or higher probability of a shot from the grassy knoll was logically incorrect. It was a 5% chance of finding a match in random noise and did not consider other possible causes.^[39]

A November 2003 analysis paid for by the cable television channel Court TV concluded that the putative gunshot impulses did not match test gunshot recordings fired in Dealey Plaza any better than random noise.^[40] In December 2003, Thomas responded by pointing out what he claimed were errors in the November 2003 Court TV analysis.^[41] In 2005, five acoustic experts (Linsker, Garwin, Chernoff, Horowitz, and Ramsey) reinvestigated the acoustic recordings and noted several errors made by Thomas.^[42]

In 2013, Professor Larry J. Sabato, Ph.D. commissioned a study on the Dictabelt recording using more modern analytical techniques.^[43][44] The report concluded that the recording did not contain sounds of the assassination gunfire and that it would be of "doubtful utility" as evidence to prove or disprove a conspiracy.

In addition to this, approximately 90% of the witnesses present in Dealey Plaza during the shooting who were cited by the HSCA reported hearing 3 shots or less,^[45] while "only a total of four witnesses, out of 178 tabulated, reported shots coming from more than one direction."^[46]

Digital restoration

In 2003, ABC News aired the results of its investigation on a program called Peter Jennings Reporting: The Kennedy Assassination: Beyond Conspiracy. Based on computer diagrams and recreations done by Dale K. Myers, it concluded that the sound recordings on the Dictabelt could not have come from Dealey Plaza, and that Dallas Police Officer H.B. McLain was correct in his assertions that he had not yet entered Dealey Plaza at the time of the assassination.

In the March 2005 issue of Reader's Digest, it was reported that Carl Haber and Vitaliy Fadeyev were assigned with the task of digitally restoring Dictabelt 10 by Leslie Waffen from the National Archives. Their method consisted of using sensors to map the microscopic contours of the tracks of old sound recordings without having to play them using a stylus, which would further degrade the sound. Dictabelt 10 was worn from countless playings and cracked due to improper storage.^[47]

With advancements in artificial intelligence, digital restoration of older analog audio is now possible with sound source separation. Machine learning techniques like a convolutional neural network can classify and identify between different types of firearms based on the sound of a gunshot from recorded audio used in crime scene forensics.^[48]

Possible origins

Left unanswered by the professional analyses was the question of whose open microphone captured the sounds recorded on the Dictabelt, if not Officer H.B. McLain. Jim Bowles, a Dallas police dispatcher supervisor in November 1963, and later Dallas County Sheriff, believes it originated from a particular officer on a three-wheeled motorcycle stationed at the Dallas Trade Mart, the original destination of President Kennedy's motorcade, along the same freeway to Parkland Hospital, which would account for the sound of sirens rushing by.^[49]

McLain believes that it was from a different officer on a three-wheeler near the Trade Mart, who was known for his whistling. When interviewed by author Vincent Bugliosi, the officer acknowledged that his microphone could have been stuck in the open position (he did not recall hearing any transmissions for several minutes), and could later have become unstuck after he followed the motorcade to Parkland Hospital.^[50]

References

1. In addition, there are two earlier open-mic portions of the recording, one at 12:24 p.m. (4.5 seconds) and the other at 12:28 p.m. (17 seconds). J. C. Bowles, The Kennedy Assassination Tapes: A Rebuttal to the Acoustical Evidence Theory 2008-08-29 at the Wayback Machine, 1979.
2. Warren Commission Hearings, Commission Exhibit 705, Radio log of channel 1 of the Dallas Police Department for November 22, 1963 June 12, 2008, at the Wayback Machine, vol. 17, p. 395.
3. Barber, Steve. "The Acoustic Evidence: A Personal Memoir". mcadams.posc.mu.edu. John McAdams. from the original on October 20, 2014. Retrieved July 20, 2014.
4. "Reexamination of Acoustic Evidence in the Kennedy Assassination," Committee on Ballistic Acoustics, National Research Council, SCIENCE, 8 October 1982, [1] 2008-08-29 at the Wayback Machine
5. "Signal Processing Analysis of the Kennedy Assassination Tapes," R.C. Agarwal, R. L. Garwin, and B. L. Lewis, IBM T. J. Watson Research Center, [2] 2008-11-21 at the Wayback Machine
6. Warren Commission Hearings, vol. XVII, pp. 390-455, CE 705, Transcription of all radio transmissions from Dallas police channel 1 and channel 2 from 12:20 p.m. to 6:00 p.m., Nov. 22, 1963 2007-09-27 at the Wayback Machine.
7. Posner, Gerald (2018). The Posner Files: Case Closed and Killing the Dream. Newburyport: Open Road Media. ISBN 9781504056182.
8. Blakemore, Bill (August 7, 2004). "Scientists Work to Preserve 'JFK' Recording". ABC News. from the original on August 19, 2014. Retrieved August 15, 2014.
9. Testimony of Dr. James Barger, 5 HSCA 650 2011-05-15 at the Wayback Machine.
10. HSCA Record 180-10120-10025, HSCA Committee Briefing, December 18, 1978, pp. 22–23.
11. Taken by Robert Hughes.
12. H.B. McLain interviewed by Vincent Bugliosi, Reclaiming History: The Assassination of President John F. Kennedy, 2007, ISBN 978-0-393-04525-3, endnotes pp. 177 & 203.
13. H.B. McLain interviewed by Vincent Bugliosi, Reclaiming History: The Assassination of President John F. Kennedy, 2007, ISBN 978-0-393-04525-3, endnotes pp. 177 & 203.
14. James C. Bowles, The Kennedy Assassination Tapes: A Rebuttal to the Acoustical Evidence Theory, Transcripts of Dallas Police Department Radio Communications, November 22, 1963, Annotated August 17, 2007, at the Wayback Machine.
15. Vincent Bugliosi, Reclaiming History: The Assassination of President John F. Kennedy, 2007, ISBN 978-0-393-04525-3, p. 380.
16. Larry M. Sturdivan, The JFK Myths: A Scientific Investigation of the Kennedy Assassination, 2005, p. 72, ISBN 978-1-55778-847-4
17. Vincent Bugliosi, Reclaiming History: The Assassination of President John F. Kennedy, 2007, ISBN 978-0-393-04525-3, endnotes pp. 202-3, citing the HSCA report, p. 84.
18. "The acoustic evidence that was the sole objective, scientific support for the existence of a conspiracy in the HSCA investigation was debunked.", Sturdivan, 2005, p. 77
19. "The more than six-hundred page draft was put aside, and a majority of the [HSCA] committee approved a preliminary nine-page "Summary of Findings and Recommendations" that concluded, based solely on the flawed acoustics findings, that there was a conspiracy to kill JFK involving a second gunman." ... "Blakely later told a journalist [Earl Golz], 'If the acoustics come out that we made a mistake somewhere, I think that would be the end of it.' " Posner, 1993, p. 457
20. HSCA Report pp. 483–499 2007-10-10 at the Wayback Machine, 503–509 2007-10-11 at the Wayback Machine.
21. "Stokes wants follow-up of conspiracy hypothesis". The Bulletin. Bend, Oregon. July 18, 1979. p. 12. from the original on January 9, 2016. Retrieved December 15, 2014.
22. Wicker, Tom (July 22, 1979). "Controversy masks key assassination finding". Eugene Register-Guard. Eugene, Oregon. p. 27A. from the original on May 4, 2016. Retrieved December 15, 2014.
23. Taken by Elsie Dorman, Mal Couch, and Dave Wiegman.
24. Letter, Richard E. Sprague to Harold S. Sawyer, March 3, 1979, pp. 1–2, Sprague Collection, National Archives.
25. Posner, Gerald. Case Closed, 1993, p. 241
26. Sheriff Decker's words were broadcast on channel 2, but they were apparently picked up by a microphone stuck open on channel 1 from the loudspeaker of a nearby police vehicle.
27. Vincent Bugliosi, Reclaiming History: The Assassination of President John F. Kennedy, 2007, ISBN 978-0-393-04525-3, endnotes p. 199.
28. Leary, Warren E. (May 15, 1982). "Study says tapes don't point to second gunman". Lawrence Journal-World. Vol. 124, no. 135. Lawrence, Kansas. AP. p. 22. from the original on January 19, 2023. Retrieved August 21, 2015.
29. Ramsey, Norman F.; Alvarez, Luis W.; Chernoff, Herman; Dicke, Robert H.; Elkind, Jerome I.; Feggeler, John C.; Garwin, Richard L.; Horowitz, Paul; Johnson, Alfred; Phinney, Robert A.; Rader, Charles; Sarles, F. Williams (1982). Report of the Committee on Ballistic Acoustics (Report). Washington, D.C.: National Academy Press. p. 2. from the original on October 14, 2008. Retrieved August 21, 2015.
30. "JFK gunman theory doubted". Beaver County Times. Beaver, Pennsylvania. May 16, 1982. p. A17. from the original on January 9, 2016. Retrieved August 21, 2015.
31. While channel 1 transmissions (routine police radio traffic) were recorded on a Dictaphone machine, channel 2 transmissions (reserved for special events such as the presidential motorcade) were recorded on a Gray Audograph machine. Both machines were located at Dallas Police headquarters.
32. FBI Record 124-10006-10153, Letter from James E. Barger to G. Robert Blakey, February 18, 1983, pp. 1–3.
33. Thomas, Donald B. (2001), (PDF), Science & Justice, 41 (1), The Forensic Science Society: 21–32, doi:10.1016/S1355-0306(01)71845-X, PMID 11215295, archived from the original (PDF) on 2008-10-01, retrieved 2013-01-17
34. Thomas, Donald B. (November 17, 2001), , archived from the original on July 25, 2008, retrieved 2008-07-30
35. Thomas, Donald B. (November 23, 2002), , archived from the original on October 26, 2009, retrieved 2008-07-30{{citation}}: CS1 maint: unfit URL (link)
36. George Lardner Jr., "Study Backs Theory of 'Grassy Knoll' ", Washington Post, March 26, 2001
37. Linsker R., Garwin R.L., Chernoff H., Horowitz P., Ramsey N.F., "Synchronization of the acoustic evidence in the assassination of President Kennedy" 2013-10-13 at the Wayback Machine, Science & Justice, vol. 45(4), 2005, pp. 207–226; and Linsker R., Garwin R.L., Chernoff H., Ramsey N.F., "Acoustic synchronization: Rebuttal of Thomas' reply to Linsker et al." 2016-03-06 at the Wayback Machine (originally published online in Science and Justice and referenced in Science and Justice 46(3):199 (2006)).
38. Vincent Bugliosi, Reclaiming History: The Assassination of President John F. Kennedy, 2007, ISBN 978-0-393-04525-3, p. 379.
39. O'Dell, Michael, , archived from the original on 2008-05-12, retrieved 2008-07-30
40. , CourtTV.com, November 2003, archived from the original on 2003-11-06, retrieved 2008-07-30
41. Thomas, Donald B. (December 2003), , archived from the original on 2008-09-19, retrieved 2008-07-30
42. Linsker, R.; Garwin, R. L.; Chernoff, H.; Horowitz, P.; Ramsey, N. F. (October 29, 2005). "Synchronization of the acoustic evidence in the assassination of President Kennedy". Science & Justice. 45 (4): 207–226. doi:10.1016/S1355-0306(05)71668-3. PMID 16686272. from the original on September 28, 2021. Retrieved September 28, 2021 – via PubMed.
43. https://thekennedyhalfcentury.com/pdf/Kennedy-Half-Century-Audio-Research.pdf 2021-09-24 at the Wayback Machine ^{[bare URL PDF]}
44. http://thekennedyhalfcentury.com/pdf/Further_research_analysis_and_commentary_on_the_Dallas_Police_Department_recordings_of_November_22_1963.pdf 2021-09-28 at the Wayback Machine ^{[bare URL PDF]}
45. . August 29, 2021. Archived from the original on 2021-08-29.
46. Reitzes, Dave (2001). "51 Grassy Knoll Witnesses". The JFK 100. Retrieved 11 January 2024.
47. . Archived from the original on April 28, 2007.
48. Raponi, Simone; Oligeri, Gabriele; Ali, Isra Mohamed (2022). "Sound of guns: digital forensics of gun audio samples meets artificial intelligence". Multimedia Tools and Applications. 81 (21): 30387–30412. arXiv:2004.07948. doi:10.1007/s11042-022-12612-w. ISSN 1380-7501.
49. Vincent Bugliosi, Reclaiming History: The Assassination of President John F. Kennedy, 2007, ISBN 978-0-393-04525-3, endnotes pp. 184–190.
50. Vincent Bugliosi, Reclaiming History: The Assassination of President John F. Kennedy, 2007, ISBN 978-0-393-04525-3, endnotes pp. 184–190.

Further reading

• Stokes, Louis (Chairman, House Select Committee on Assassinations). (29 March 1979). Report of the Select Committee on Assassinations of the U.S. House of Representatives.
• Ramsey, Norman F. (Chairman, Committee on Ballistic Acoustics, National Academy of Sciences). (1982). Report of the Committee on Ballistic Acoustics.
• Posner, Gerald (1993), Case Closed, Random House, ISBN 0-679-41825-3, OCLC 185413533 (pp. 238–242, unraveling of acoustic evidence in JFK conspiracy finding)
• Thomas, Donald B. (14 June 2000). Science & Justice 2001 41, 21-32.
• Thomas, Donald B. (17 November 2001). .
• Thomas, Donald B. (September 2002). .
• Thomas, Donald B. (23 November 2002). .
• O'Dell, Michael. (2003). .
• Berkovitz, Robert. (19 November 2003). .
• Thomas, Donald B. (December 2003). .
• National Research Council, Washington, DC 1982 Report of the Committee on Ballistic Acoustics
• March 2005 Reader's Digest article
• Sturdivan, Larry M., The JFK Myths: A Scientific Investigation of the Kennedy Assassination, 2005, ISBN 978-1-55778-847-4.
• Belin, David W., Final Disclosure: The Full Truth About the Assassination of President Kennedy, 1988, Macmillan, ISBN 978-0-684-18976-5.