BRUEL & KJAER 4188 - Effect of Humidity

Chapter 3 — Prepolarized Free-field
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" Microphone Type 4189
Effect of Humidity
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Microphone Handbook
Brüel & Kjær
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3.13 Effect of Humidity
Due to the microphone’s high leakage resistance, humidity has, in general, no effect
on the microphone’s sensitivity or frequency response. The microphone has been
tested according to IEC68–2–3 and the effects of humidty on the sensitivity at
250Hz and the frequency response have been found to be less than 0.1dB at up to
95% RH (non-condensing) and 40°C.
Fig.3.24 Typical effect of ambient pressure on actuator response
(a) at 101.3kPa (b) –40kPa change (c) –80kPa change
(d) at 2kPa
Fig.3.25 Typical variation in sensitivity at 250Hz from that at 101.3kPa as a function of ambient
pressure
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1k 10k Frequency (Hz)
– 20
– 10
10
Response (dB)
0
30
500
50k
20
(d)
(b)
(c)
(a)
1 10 100 1000Ambient Pressure (kPa)
– 6
– 4
0
Response (dB)
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– 2
2
4