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APPENDIX D
POSSIBILITY OF SUPERPOSED RECORDINGS
The Committee considered seriously the possibility that the impulses
analyzed by BRSW/WA might have been overlaid at a later time by the "hold
everything..." message; if that had occurred the presence of the message
would not automatically imply that the impulses occurred well after the
assassination. The Committee examined four kinds of evidence on the
possibility: (1) physical evidence concerning overrecording or Dictabelt
substitution, (2) likelihood of possible scenarios for overrecording, (3)
compatibility of "hold everything..." timing with other firmly established
evidence, and (4) recorded acoustic evidence on the recordings such as the
characteristics which show that the recorded cross talk passed through a
radio receiver with automatic gain control (AGC). These four kinds of
evidence are discussed below.
(1) Physical evidence concerning overrecording or Dictabelt
substitution
The original DPD Channel I Dictabelt was examined by some Committee
members and by William Sturtevant of the Dictaphone Corporation for
possible physical evidence of a double recording. No indications of
superposed recordings were found. The track in the region of the "hold
everything ..." expression was examined with particular care. The tracks
were remarkably clear and parallel and showed no indications of superposed
recordings.
There was considerable writing with a china marking pencil on the
surface of the Dictabelt. The markings give in one handwriting "11-22-63,
PL2" and an encircled "10". The times 12 5 and 12 40 in a
different handwriting also appear as do the letters J and H. These
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markings were similar to those on the other Dictabelts made that day. A
photograph of the Dictabelt has been submitted to Ms. Doris Schwartz, who
serviced the recorder during the period in question and who now lives in
Duncanville, Texas. Although Ms. Schwartz does not recognize the other
handwriting, she does identify the "11-22-63, PL2, 10" as her own
handwriting. She uses an unmistakable 2 and feels that the specimen is the
original belt. With this identification, any substitution of a different
Dictabelt for the original could not have been accidental; it would have
had to be deliberate, and it would have involved counterfeiting the writing
for the date and belt number .
(2) The likelihood of scenarios for overrecording
Although there is good reason to believe that the belt examined was
the original one, the Committee also considered the possibilities that the
belt examined might itself have been a later copy of an earlier Dictabelt
with a double recording, in which case the physical examination would not
show evidence of superposed recordings, or might have been a copy
substituted for the original with the "hold everything..." superposed while
copying. To explain in one of these ways the presence of the "hold
everything..." phrase except by deliberate intent would require an
incredible array of accidents, each of which is highly unlikely. For such
accidents to have occurred immediately following the assassination, the
Dictabelt would have had to be knocked backward by just one minute of
recording time, this unprecedented accident would have had to occur within
the first minute following the assassination, it would have had to occur in
a manner to leave no acoustic evidence, and in addition someone
irresponsibly would have had to copy the DictabelL, counterfeit the
identification writing, substitute the new Dictabelt for the old one, and
throw away the original, despite both the importance of the case and the
well known police requirement not to destroy evidence O
Comparable difficulties confront the hypothesis that there was an
accidental superposed recording at a later time. In that case, the
Dictaphone playing potential evidence of a presidential assassination would
have had to be carelessly set to record instead of listen, and a recording
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of Channel II at the same time would have had to be playing accidentally in
the background. In addition the Channel II playing would have had to be
set accidentally to the very narrow range that could indicate
incompatibility; if the setting had occurred one minute earlier it would
have produced no problem and one minute later it would have been detectable
as an impossible timing. The double recording would have had to continue
at least two minutes to account for the cross talk discussed in Appendix C.
Further, there would have had to be an irresponsible substitution of a
copied Dictabelt, with counterfeited written identification and a
subsequent loss of the original, to obscure physical evidence of a double
recording. For all this to occur by accident again seems highly unlikely.
Similar difficulties face the hypothesis that the original Dictabelt was
copied to another Dictabelt, that the cross talk was picked up during the
copying, that the second Dictabelt was accidentally substituted for the
original, and the original was destroyed.
There are comparable difficulties in attributing the presence of the
"Hold everything..." message to a deliberate superposed recording and a
deliberate effort to conceal this action. It is particularly difficult to
believe that within the first minute after the assassination someone
deliberately knocked backward the Dictabelt to confuse the interpretations
of the transmission from the open microphone. No one knew in advance, or
even at the time, that there was to be an accidentally open microphone or
where it might be located. No one could tell in advance how much to
displace the Dictabelt to assure that the next transmission of cross talk
between Channels I and II would be exactly superposed on the assassination.
No one knew in advance there were impulses that would years later be
interpreted as assassination shots or that the cross talk between the two
Channels would eventually be interpreted at an even later time. Anyone who
substituted a copy of the tape to hide the physical evidence of a
superposed recording, and who counterfeited the written identification
exposed himself to a serious risk of being caught in exchange for a
potential benefit that was remote and unlikely to materialize.
Similar difficulties are presented by the hypothesis that the "hold
everything..." message was deliberately added at a later time. Since the
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message appears on the original Dictabelt and on a copy made by James
Bowles in March 1964, the deliberate superposed recording would have had to
be made before this date, long before the BRSW/WA analysis indicated there
might be information worth confusing. It could not be apparent in advance
that the "hold everything..." expression would ever be correctly
interpreted. The person deliberately faking this evidence and then
substituting a new recording with a counterfeit identification for the
original one faced a large chance of being caught in exchange for only a
very small chance that the deception would be either necessary or helpful.
It seems equally unlikely that such an elaborate and risky substitution of
forged evidence would have been made for any other reason, such as to cover
up a broadcast of an embarrassing remark.
In summary, all the possible scenarios by which a copied Dictabelt
with a forged identification could have been substituted for the original
seem highly unlikely.
(3) Compatibility of "hold everything..." timing with other firmly
established evidence.
Since the "hold everything..." expression on Channel II occurs
approximately one minute after the expression "Go to the hospital...,"
hence, more than one minute after the assassination, and since the Channel
I recorder ran continuously during much of the subsequent time 9 the cross
correlation between the two channels has implications for the timing of
some other events following the assassination. Some of this other evidence
is unreliable, but some is firmly established. The Committee examined such
evidence to be sure there was no incompatibility between the timing
sequence implied by the "hold everything..." identification and the firm
limits established by other evidence. Some of these limits are discussed
in Appendix C where it is noted that later cross talk between the two
channels is compatible with this identification.
A quite different test is implied by the sounds of sirens, as
discussed in Appendix E, where it is shown that the time interval between
the assassination and the appearance of siren sounds is compatible with a
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reasonable speed of the motorcade to the hospital, provided that the
microphone picking up the siren sounds is at the Trade Mart or some other
point closer to the hospital.
Finally, the time announcements on Channel I provide further support
to the assumption that there was no double recording. The last time
announcement on Channel I before the conjectured shots and the "hold
everything..." statement was "12:28" and the first time announcement
thereafter was "12:34," a nominal difference of six minutes. When the
Channel I recording is run at a speed that reproduces the recorded hum at
60 Hz, the elapsed time between these two announcements is 389 seconds or 6
minutes 29 seconds in full agreement with the six minute nominal
difference, since the time announcements were at irregular intervals and
never included seconds. If the recording head had been moved back by 64
seconds of recording time to superpose a later "hold everything..." on top
of earlier recorded acoustic impulses, the elapsed time between the 12:28
and 12:34 time announcements would have been 453 seconds or 7 minutes 33
seconds in disagreement with the time announcements. It should be noted,
however, that the time announcements were not highly reliable since they
were obtained from a variety of different time indicators, so this evidence
alone while being supportive of the Cornrnittee's position, should not be
regarded as conclusive. It should also be noted that by timing
measurements over a wider range, the BRSW report, page 33, concludes that
the Channel I recorder "operated continuously"; a 64-second recording
overlap would be a marked discontinuity. If it were argued that a
superposed recording occurred by a Dictabelt displacement which corrected
itself before the 12:34 time announcement, a groove cutting at a different
angle and spacing should have been observable, and no such groove was seen
during the physical examination of the Dictabelt. Furthermore, such a
scenario would leave intact the evidence from Appendix C that the relevant
acoustic impulses occurred well after the assassination.
(4) Recorded acoustic evidence on the Dictabelt, such as
characteristics which show that the recorded cross talk passed through a
radio receiver with automatic gain control (AGC).
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From Figures B-4, B-5 and B-6, it is apparent that there are
heterodyne tones present on Channel I which do not exist on Channel II. In
fact, these tones are the key to the demonstration that the underlying
Channel II sounds present in Channel I were recorded via radio and not
at some later time.
Close attention to these Channel I heterodyne tones which are not
present in Channel II at the same time, shows that this tone is followed
immediately (over a period of about 30-50 milliseconds) by a rapid
suppression of the Channel II signal, which then assumes a constant value
for the duration of the tone. At the end of the Channel I tone, the
Channel II transmission rises over a period of 100-200 milliseconds to its
original value. This is to be understood if the Channel I tones are
heterodynes caused by additional transmitters appearing on the Channel I
band, and dominating the open-mike transmission. Thus, the radio receiver
will readjust its automatic gain control (AGC) to maintain a steady
(intermediate-frequency) signal level in its output. (See the heterodyne
beginning at "A" in Channel I on Figure B-4.) This is natural for such
radio receivers. At the end of the presence of the strong carrier signal,
the AGC readjusts to provide a steady output level for the open-mike
transmission. Hence, any probing tone on the microphone will suffer this
same variation due to the AGC action in the presence of a sudden
interfering carrier on Channel I.
..
b
In many cases, however, there is present in the Channel I output a
brief tone, of strength similar to those noted in the previous paragraph,
which is present also in Channel II. These brief tones in no case show a
change in level at the beginning and end. (See the Channel II heterodyne
marked t1C't on Fig. B-4.) This is to be understood because they enter the
open microphone and are broadcast at a steady carrier level on Channel I.
Whatever behavior there was of AGC on Channel II is reflected in the level
of the heterodyne on Channel II, and there should be no further distortion
of this level by action of AGC on Channel I.
This analysis demonstrates that cross talk from Channel II was
directly recorded onto a Channel I recorder through a radio receiver and
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not at some later time coupled either by electrical or acoustical coupling
into a recording of Channel I. Had this latter taken place, there would
have been no difference in AGO action on the heterodynes recorded only on
Channel I from that of the brief tones present in Channel II as well. This
is true, independent of any assumption that might be made of automatic
level control on subsequent recordings.
The crucial evidence within the "hold everything..." interval itself
occurs in a 0.5 seconds region of the Channel I recording shown in Figure
B-6. This corresponds to Channel II times of 32.00-32.50 seconds, aligned
with the corresponding signals on Chanel I. Note that the Channel II
recording is the recent one made by this Committee from the gray Audograph
disk' without ttrepeats.l' The suppression of a Channel II heterodyne is
seen in Figure B-6 and has been demonstrated quantitatively by the digital
data plotted in Figures B-7 and Be-.
Although the above evidence on the recordings shows conclusively that
the "hold everything..." and other cross talk phrases were recorded through
radio communication and not by later copying, there is other acoustic
evidence on the recordings as well that supports the conclusion that the
Channel II cross talk was recorded on Channel I at the actual time and not
in later copying. The phrases "You want me..." and "I'll check all these
motor cycle radios" present on Channel I are derived from Channel II.
However, on Channel I, the time difference between the beginning of these
two phrases is 15.70 seconds, while on Channel II it is 12.80 seconds - a
difference of 2.9 seconds. This time difference can not be due to a
forward skip of Channel II on playback or a backward repeat on record since
2.9 seconds is not an integral multiple of the 3.58 seconds Audograph
turntable period at this time, as measured by observable print through on
the recording. If the Channel I recording is made at the actual time, this
difference is easily attributed to the sound actuated Channel II recorder
having stopped for 2.9 seconds between these two phrases, while the Channel
I open microphone recording continued on without interruptioon. This
accounts naturally for the 2.9 second difference; but if the Channel II
reocording had been later overlaid onto Channel I the timing of the two
would normally have been identical, not differing by 2.9 seconds . The
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timing analysis was made between tapes for which the best warp between "You
want me..." on the two tapes was 0.988 while that for "I'll check all
these..." was 0.991.
Finally, if one wishes to criticize the "hold everything..." evidence
on the grounds that the Dictabelt is a copy and not the authentic original
Dictabelt, then he must also recognize that all the acoustic evidence
interpreted as favoring gunshots also comes from the same unauthentic
source.
As a result of all these considerations, including especially the ones
showing that the cross talk passed through a radio receiver with AGO, the
Committee determined that there was conclusive evidence that the "hold
everything..." expression was recorded on Channel I at the same time as on
Channel II and that the acoustic impulses attributed to gunshots were
recorded well after the President was shot and the motorcade had been
instructed to go to the hospital.
Representative terms from entire chapter:
superposed recording
