BRUEL & KJAER 2209 - Condenser Microphone

4.2. CONDENSER MICROPHONE
A condenser microphone consists essentially of a thin metallic diaphragm
mounted in close proximity to a rigid back plate. They are electrically
insulated
from one another and form the electrodes of a capacitor using air
as
the insulator ( Fig.4.2). A stabilised DC polarization voltage maintains a
dB
+1
-1
- 5
-10
-15
- 20
Insulator
Bock
Hole for static pressure equalization
Fig.4.2. Schematic of condenser microphone
•
DDDDDDDDDDDDDDDDDDDDDDDDDDDOODDD
20
50
100
200
free-field response
pressure response
free-field response wi th
UA 0055
p
500
1000
2000 Hz 5000
F
Fig.4.3. Typical frequency characteristics
of 4145
10000
20000
169t'<f'2
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