BRUEL & KJAER 1022 Instructions And Applications page 35

Example:
50 dB Range Potentiometer.
Paper Speed 100 mm/sec.: Use the section "50 dB 10 mm/sec."
and divide the measured result by 10,
see also Fig.5.13.
Range Potentiometer : 50db
Paper. Speed :
10ommjsec.
·Reading :-
5.5sec.•O.i•0.55sec
( 6 (85'6 .
Fig.5.13. Use of Protractor SC 2361, ten times higher paper
speed used than on the proctractor (50 dB 10 mm/sec.).
Reading then divided by 10 i.e. 0.55 sec.
Airborne Sound Insulation
A means of automatically carrying out this test is shown in Fig.5.14. The
wall under test is placed between two rooms, which are termed "the trans-
mitter room" and "the receiver room" respectively.
In each of the two rooms separated by the wall is placed a Type 4145
Condenser Microphone individually coupled to a Preamplifier Type 2619.
Two extension cables connect the microphone units with the Two-Channel
Microphone Selector 4408. The Microphone Selector is remotely controlled
by the two-channel switching device, which is "built-in" to the Level Recor-
der portion of the Automatic Frequency Response Recorder 3308. A 50 dB
Range Potentiometer can be used, the 1022 should be frequency modulated
and the loudspeaker (or loudspeakers) placed so that a sound field, as dif-
fuse and isotropic as possible, is built up.
By means of the Microphone Selector which is connected to the Measur-
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