Welch Allyn GSI 38, Руководство по обслуживанию

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For 8 KHz
ANSI Standard RTL for 0. dB HL
13.0 dB SPL
(+)60 dB HL (+) 60.0 dB SPL
60. dB HL 73.0 dB SPL
When calibrating using a Sound Level Meter (SLM) it is important to add or subtract the
appropriate microphone correction. When the microphones are calibrated the
manufacturer or calibration facility should supply the microphone’s frequency response
curve. The microphone is then calibrated to the SLM which has a flat frequency
response by using a piston phone or similar standard device. Below is an example of
a microphone frequency response curve.
MICROPHONE
CALIBRATION CHART
l
5
dB
+1
0
-1
-5
-10
- 1 5
Provo,
Utah
20 Hz 50 1DO
200 500 1K 2K 5K 10K 20K 50K 100k 200K
The curve shows that the microphone response is flat between 20 Hz and 1.5 KHz,
high between 2 KHz and 6 KHz, and low at frequencies 8 KHz or greater. Using 4 KHz
as
an example when a standard force is applied to the surface of this microphone its
output is 1 dB high. Therefore, when calibrating 4 KHz using this microphone we must
add 1
dB
to our expected value. Our formula for determining the proper calibration
level for 4 KHz is as follows:
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