PROJECT VISIT TO (SANITIZED)

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-03300A001900110006-2
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 3
• Document Creation Date: December 22, 2016
• Document Release Date: May 3, 2011
• Sequence Number: 6
• Publication Date: November 20, 1957
• Content Type: MEMO

Sanitized Copy Approved for Release 2011/05/03: CIA-RDP78-03300A001900110006-2
b NTIAL
20 Jcv shear 1957
BUW= I Pr 3.at Visit to ACA
1. AND Cr NEW=: The amt img v em held Friday,
15 Pov.aalaer , a
a. had p tared a tratim of the type 1A
adcropboaee us w a c ae and two stage transistor preneplifte9r. The
two stale eaglifie, paokm . included a step-up trs S rrr. The NA
slat eerare is a cut-dorm saeioo of the type B unit (about 8 db 49wa).
It is oe stn votedt with a ay1.r dupe r need Its vol" coil is d
for 50 cbis. The unit is d.sjgaed to accept a probe hmming that screw
cot. the treat portion of the micropbonr cam. Ai*, the oars or 2 stags
preamplifier package am be operated with the mdcr+mphooe 1ntapeal3y or
physically separated and virus ran tyres the mic cpbomee to the am1itisr.
Listening tests ream aeneb*ted uads r the ralleawIngg casditismat
tl)
(2)
(3)
(4)
The type TA aim into the cos stage pr m .
The type PA Me rophose into the 2 stye por amp
with its trsostoe sr input.
The type YA mike into a eon mere ial vacuw tube
aaplitieec.
With and without the probe attachment.
AltbomO the tests coasAuated wore aa3y of a prslislawy natfre,
the a arsipaed Mss veil pleased with the resents. 2aa 2 stye prsseap
peck ge was vary epeist and n claim the overall ipaahsge is only abaft
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CONF!DENT LAL
2 db worse (s/n) then using the mike with a vacutsa tubs arrengsaoent.
The ZA mike vitbout pr.sQ can be used with or without a probe ( the
probe housing being not integral with the aike) and rryresents in a
minlanm package rise a high quality atlw ubase only dr wbeck is the
fever all crvvolts of output available tar a given sound input.
A prototype IA mike without prssop was given to the taadar-
signed for further testing (the preanatp]Cter portion together with the
aecessery, AP units are to be fattsrdod in about ton dys). 0 plans
to deliver am each of all the bardwarrd discussed to data and pending
the outcor of APD tests, a declaim will be made as to vtot further
hardware ICA will produce (and In what form) under this task.
b. repotted the following as rs rds the wire-
less hearing pnow project
(1) The essential pre blare to be solved is the denralcpesnt
of a sward traneducenr swell enough to fit into the specs of the
sor canal yet sensitive enough to respoctd to the audio power
available frog the rf portion at the circuit.
(2) *ttaats at the dsretl+ttpssnt of a sagnertie sound teams.
duasr nesting the nooessary requi reelents were set sUccssOM.
(3) Al the use of castal traneduser was a definite
possibility, felt that the jOb VWAM be a rsethaar fOCU dable
an and required to develop a aneoasstal ter ewer.
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me directed to prepare a final report as this p eject 25X1
Aetalli g sues and failures of the currant In additiaaa,
this report will contain ions as to at felt Oft"d be 25X1
done in solving the paroblen die' ardditiaaal r3'!'bart neare put into the
prc .
c. denonstrated the various directir al gale ro? 25X1
phones devee3+ep tat tog coalmen of the puns. The 60"Itjens were
stalls" to Uses previously described in earlier reports. The two
aicrephones of not interest wore the .Oh" oes( easor and the 12' cir-
cular line era'rep. (Bath of these mikes have also been d scribed in
detail in previous reports.) Although the directional efficiency
of the 24" condenser vacs an3 about 2 db better at 1000 gyclae than
the lime array, the undeersign d felt that from the listening tarts
conducted the comd ns r unit vacs wits a bit better. Of women, it the
line array wee or the sacs effective area M the coadowgr, it would have
4 a' 7F TIAL
Sanitized Copy Approved for Release 2011/05/03: CIA-RDP78-0330OA001900110006-2
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OT, ~ 7 r a V E1\ I A L
-I-
been better since it combines the directional properties of a hies ar
with those at eireu]ar ring piston m1crop . Norsvs , an array of
this type would be difficult to package for easy tr n@pcrtation and
would inv lve very car,Ayi construction in carder to obtain the diesired
properties.
this projrc w will be a detailed _W- :W..a .w.. "'+N_ rye OR
?s the results Obtained
Meem"T
together with 40ti toe
st nIated to rst our SAW haa4w" that should be om-
revirements.
d. presented a tape recording of the results
obtained with wis se reducing device. Otis reeding was as41 with
the device, utilizing 004 700-3O0 ape bandvidtke and not using awy
s
1 L, to b:r orry!- AVC circuit for es x ahan"I groupIft. The test results
v migoe i did not indicate - thet any iawprurarent
the was
test sal (Oormisting past by using the ewipetestt. Novoves, the
at sreecft and nQ
ratio) *s rather a ssrW* care and theitOSUlts~ Mky net ~ die
of what can be clods it a better slaeanoise was used. be motive
in previous repo rte deciding on a pre tasting method is a sexism
p l,em. The undaacslgssed believes that the only WW in which this
devise viii fsnaliy powers its writ or failure is to utilise re rdsngs
ayes U0 4W opesa-ting ditions which bay to be difticuit to
t mmeribe and 4vtorming, it the moles reamer M,ses the tronecriptson
difficulty air its the aasunt Of infaersatian that =a be a tr ctsd.
Seas UMMS theret+ei.s should be tried to obtaip ruck test rscrrdirag
from field p (in XW10h) which can be us" for swab a test.
Distributions
Orig. P-189
1 - !-tlol
1 -l-ll~t
1'P.185
1 - Irmo
W s1s (90 NOV 1957)
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