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Report of the Committee on Ballistic Acoustics (1982) / Chapter Skim
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II. DESCRIPTION OF STUDIES BY BRSW AND WA
Pages 8-11

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From page 8...
... Because of the severe noise and distortion on the recording, the BRSW team could neither confirm that this segment contained gunshot sounds, nor eliminate the possibility that they were present, by simple listening or by examining the waveforms of sounds on the tape. Therefore, they went to Dealey Plaza in Dallas August 27, 1978, and made recordings of test shots with various kinds of guns and ammunition, two shooter locations, and many microphone locations along the approximate route of the motorcade.
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From page 9...
... The BRSW team then compared, manually, each of 432 test shot waveforms with all the parts of the 5 1/2 minute record that could reasonably have included assassination gunshot sounds. This comparison was done using a binary correlation metric, with a ±6 msec window, applied to strip chart recordings of the relevant waveforms.
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From page 10...
... After a set of echo producing objects had been identified, a theoretical model of sound propagation in Dealey Plaza, incorporating possible variations in shooter position, microphone position and velocity, and air temperature, was used to predict the relative timings of various echoes that would be expected in the actual Channel I recording if the segment in question contained the sounds of a gunshot fired from the grassy knoll. In effect, for every choice of shooter position, microphone position, microphone velocity and air temperature, WA could theoretically determine the time of impulses of a hypothetical test shot, which they use the print version of this publication as the authoritative version for attribution.
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From page 11...
... On seeing the WA results, the BRSW investigators agreed that their earlier screening procedure had missed the WA identified segment and that the WA identification should be used. The waveform now identified by both BRSW and WA as the sound of a gunshot fired from the knoll is shown in Figure 2 with the WA identification of the muzzle blast being at B
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Key Terms

  • test shots
  • binary correlation
  • print version
  • assassination shot
  • assassination shots

  • brsw team
  • suspected assassination
  • microphone position
  • microphone locations
  • suspected shot

  • shooter position
  • shooter location
  • muzzle blast
  • dealey plaza
  • msec window

  • chart recordings
  • strip chart
  • air temperature
  • gunshot sounds
  • false alarms

  • typical test
  • reconstructed test
  • hypothetical test
  • microphone location
  • brsw suggested

  • brsw selected
  • brsw investigators
  • assassination gunshot
  • microphone velocity
  • actual assassination


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