VISIT TO (SANITIZED)

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-03172A000300050027-6
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 2
• Document Creation Date: December 22, 2016
• Document Release Date: April 10, 2012
• Sequence Number: 27
• Publication Date: August 2, 1956
• Content Type: MEMO

Declassified in Part - Sanitized Copy Approved for Release 2012/04/10: CIA-RDP78-03172A000300050027-6
U
2 August 1956
1. Time and Place of Meeting:
27 Jk4y 1 , at
2. Attendances
3. Discussion:
a. P-109B Contact Microphone
is continuing with wall and intelligibility tests.
brought up the subject of wall measurement bX--
Fo miloaded, Rochelle crystals, obtained from ~ were
delivered to wants to load se crystals in a different
manner and to a lesser degree than has done. ____has checked
;O_M_~
the is and, in general them accurate and reliable.
Hoverer, does not agree wit} on thet of having a highly
sensitive, narrow range crystal microphone. believes that the
frequency should be broader, even if sensitivity has to be
reduced. refers a frequency range from 500-000 cps and is
not primarily concerned with filtering out any of the higher
frequencies at this time.
L__]stated that the crystals must be shielded and are now
in the process of shielding all the microphones being used on this
projects has to the same conclusion and have now shielded
their microphones. 7 states that this reduces the ambient noise
picked up.
ultra-son ics. He became aware of our interest In s net r through
contact with the work is doing on measurement by neutron back-
scattering. stated that he considered it feasible, to use
a reflector ultra-sonic measurement instrument, instead of one based
on the resonance principle.
I ^~ ? ? Acv L Tr 23JL-1 &O a-
?, 5'-C- V31 : Try
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JEST 2 Z NEXT AUT4: Pt
Declassified in Part - Sanitized Copy Approved for Release 2012/04/10: CIA-RDP78-03172A000300050027-6
 Declassified in Part - Sanitized Copy Approved for Release 2012/04/10: CIA-RDP78-03172A000300050027-6
on the resonance principle. stated that the reflective
signal should be at least 54 accurate. For exwVle, if the distance
indicated by the measurement is 6 inches, it would be was to drill
3 inches. Repeat measurements could be taken, darn to the final
measurement, which should be accurate within 5%. Also, accuracy
should improve with declining wall measurement.
(
would like to submit a proposal for a quick feasibility
25X1
study. A reflector sonic measurement instrument can be rented
on a monthly basis. ult7stated that the study could be completed
25X1
within two months and would cost approximately $2000.
This study would be similar to the one conducted by US
under Ad Hoc #25. However, the Bureau had only considered resonant
ultra-sonic devices and so far has not come to any definite conclusions.
The possibility of Wing microwaves, as proposed by 1?8, still has
not proven feasible and the Bureau, due to personnel shortages has
been able to devote very little time to it. Therefore, the
proposal, in the opinion of the undersigned, looks good and should
be accepted.
188 APD
Distribution:
P-109D - Orig.
Ad Hoc #25 - 1
AWS - 1
Chrono - 1
188/APD/AWS/bf (2 Aug 56)
Declassified in Part - Sanitized Copy Approved for Release 2012/04/10: CIA-RDP78-03172A000300050027-6