Boxoffice-11.04.1950

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Screen Tests Show Low
Sound Losses
Sound transmission tests recently made
in Hollywood have established the Starke
Custom Cycloramic motion picture screen
as considerably superior to standards prescribed
by the Society of Motion Picture
and Television Engineers, it has been disclosed
by the B. F. Shearer Co., manufacturers
and distributors of the screen.
The tests were made by Donald P. Loye,
for many years chief acoustical engineer
for Electrical Research Products, Inc.. and
Western Electric. Ti-ansmission measurements
revealed that at critical frequencies,
losses in the Cycloramic screen are considerably
lower that the maximum established
allowable loss. At 6,000 cycles, according
to Loye's findings, transmission
loss is less than half that permitted by the
SMPTE standard, while at 10.000 cycles
the loss is only 40 per cent of that judged
acceptable.
To conduct the tests, liOye used a 10x14-
foot screen of three layers of cloth with
no welt separating the front and middle
layers. It was mounted on a portable
wood frame. Measurements were made
with a loudspeaker fed by an audio oscillator
and amplifier behind the screen and
a calibrated microphone amplifier and output
meter in front.
The microphone which was used to pick
up the sound was placed in six different
vertical positions and also at distances
ranging from six to 16 feet from the face
of the loudspeaker baffle. In each position
the response was recorded by a highspeed-level
Bell Telephone Laboratories recorder.
A continuously variable sweep
frequency oscillator, ranging from 50 to
10,000 cycles per second, was connected to
the amplifier and loudspeaker system, and
the standard theatre equalization for the
purpose of reducing high frequency response
was disconnected during the tests.
Since its appearance on the market a
little more than a year ago, the Cycloramic
screen has been installed in nearly 1,000
theatres in the U.S. and foreign countries,
the Shearer firm reported. Among features
claimed for it is the contention that
it is practically indestructible and that it
may be viewed from front and side seats
with no distortion and with a "third dimensional"
effect.
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