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1.
Purpose
Type 4230 is a portable lightweight acoustic calibrator for accurate field
calibration of sound level meters and other sound measuring systems. It fits
all B & K sound level meters and microphones of
1
in and 1/2 in diameter.
A unique construction gives a high equivalent volume of the calibrator, and
the sound pressure developed is, therefore, independent of microphone vo-
lume. This means that exact fitting of the microphone in the coupler is not
critical, and that different microphones can be compared without correction
for equivalent volume.
The calibrator is virtually unaffected by variations in static pressure and
works accurately within a wide temperature range.
The sound pressure level developed is 94 dB re 2x1o-5 Nfm2 (1 Nfm2) and
the accuracy of calibration is better than
±
0.3 dB. A frequency of 1000 Hz
has been chosen, to give independence of the weighting networks A, B, C
and D used with many sound level meters. These have a common reference
at 1000Hz.
The operation of the calibrator is extremely easy: just fit the microphone
into the cavity, press the button on the calibrator and adjust your meter to
correct reading.
3
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