BRUEL & KJAER 4131 - Page 27

~
UJ
(!)
+1
0
-1
dB
-5
\
1-- 4135
~ -10
:I:
u
-15
0.1
l\
--
-
4136
--..
0.5
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....... ~
5
GENERAL
CHARACTERISTICS
...........
.........
............
'
~
1'-.
""'
10 atmospheres 50
100
STATIC AMBIENT PRESSURE
/Ui&D!.
Fig. 1.22. Variation of the quarter-inch microphone sensitivity as a function of
the static ambient pressure. Measurements made down to 14 mmHg (o.02 atm. ,
or 26 Km- 86ooo ft. altitude) show that the sensitivity in vacuum would be less
tlwn 1 dB higher than the sensitivity at 1 atm. (Only valid up to 3ooo Hz.
4135
Influence of
low pressures·
on response
1dB
10000
10
kc/s
See below).
;· ,,;
. Ii'iii~r = t==
60
2~ .==
3~ - ~
i i•D tl
.IOOQe 1()()()0e'jM
100
4136
Influence . of ,_ .
60
low pressures ' ·
on response
,, .._ __ ..
1 dB
100001 20000
10
kc/s
Fig. 1.23. Influence of the static ambient pressure on the frequency response
of the quarter-inch microphones.