BRUEL & KJAER 4188 - Page 101

Chapter 4 — Free-field
1
/
2
" Microphone Type 4190
Effect of Ambient Pressure
Falcon™ Range of Microphone Products
Microphone Handbook
Brüel & Kjær
4
−
26
The typical pressure coefficient at 250Hz for Free-field
1
/
2
" Microphone Type 4190
is –0.010dB/kPa, well within the
±
0.03dB/kPa limits required for Type 0 and Type
1 sound level meters by IEC651.
Fig.4.26 Typical variation in frequency response (normalized at
250Hz) from that at 101.3kPa as a function of change in
ambient pressure
Fig.4.27 Typical effect of ambient pressure on actuator response
(normalized at 250Hz) (a) at 101.3kPa (b) –40kPa
change (c) –80kPa change (d) at 2kPa
940763e
1k 10k Frequency (Hz)
– 1
0
2
Correction (dB)
1
3
500
50k
– 10kPa
change
– 20kPa
change
– 40kPa
change
940755e
1k 10k Frequency (Hz)
– 20
– 10
10
Response (dB)
0
30
500
50k
20
(d)
(b)
(c)
(a)