-2,50
-2,00
-1,50
-1,00
-0,50
0,00
0,50
1,00
1,50
2,00
2,50
100
1000
10000
100000
f[Hz]
L[dB]
Fig. 1.4. Typical free-field frequency response of WK-21 microphone.
1.5. Influence of operating environment
•
Influence of static pressure
-0.01dB/kPa (for 1kHz)
•
Influence of temperature
-0.003 dB/°C (for 1kHz)
•
Influence of humidity
≤
±
0.1dB (without condensation)
•
Influence of electromagnetic field
conformable to EN 61672-1:2003
specifications (maximum when
microphone extension cable is
parallel to field direction)
•
Influence of electrostatic field
conformable to EN 61672-1:2003
•
Influence of a.c. power-frequency (reading in 80 A/m field intensity)
-
at A frequency weighting
not detectable
-
at C frequency weighting
≤
30.0dBC
1.6. Influence of instrument accessories
Installation of additional equipment does not deteriorate accuracy class of the instrument,
however some influence of this equipment on entire instrument performance can be detected.
•
Influence of microphone extension cable
its connection to the instrument
causes nonlinear distortion
increasing with frequency at high
input signal levels – see table
below.
f [kHz]
1
2
4
5
6,3
8
10
12.5
16
20
25
135dB 0.07% 0.07% 0.08% 0.08% 0.08% 0.09% 0.09% 0.15% 0.98%
1.9%
1.7%
130dB
0.06%
P
D
5
L
6
125dB
0.03%
•
Influence of windscreen (at 0
°
incidence)
See table below and Fig. 1.5.
