The acoustic records contain several events, which enable testing how Channel-I would record a brieftone generated on Channel-II. In particular a loud annoying brieftone accompanied the Channel-II broadcast by Sgt. Bellah. On Channel-I the brieftone, though slightly attenuated by about three db relative to the voice, is still a conspicuous annoyance. The Bowles tape of the Dictabelt is the source of these wave files.
The significance of this event goes beyond showing that a loud brieftone would have accompanied true Decker crosstalk. Spectrographs of the initial portions Bellah's Channel-II broadcast and his message on Channel-I show brieftones with exactly the same 1.68 kHz frequencies.
| Spectrograph of the Bellah Broadcast |
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| Spectrograph of the Bellah Crosstalk |
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The acoustic research community acknowledges that James Bowles slowed the playback of the Dictabelt and produced a tape with a frequency compression of about 5 percent. As a result the frequency of the 60 Hertz power line hum measures about 57 Hz on his tape. Correspondingly a 1.68 kHz brieftone recorded onto the Dictabelt would have been recorded on the tape as a 1.60 kHz tone. So finding a 1.68 kHz brieftone on the our copy of the Bowles tape proves that it is an untrue record of the Channel-I receptions by the DPD at approximately 12:30 PM of November 22, 1963.
Now suppose that James Bowles did not slow the Dictaphone during taping. This alternative would allow true Bellah crosstalk and does more than invalidate the matching of pulse patterns from test shots with the Bowles tape of the Dictabelt. Under these conditions the finding of matches that required an unnecessary, and therefore an improper, adjustment for frequency compression would be overwhelmingly strong evidence that a studio amateurishly added the pulse patterns to the acoustic record. Hence the earlier conclusion that the Bowles tape is an untrue record of the Channel-I receptions would still stand.
