8
-3,0
-2,0
-1,0
0,0
1,0
2,0
3,0
100
1000
10000
100000
Fig. 1.4. Typical free-field frequency response of MK-401 microphone
1.5. Influence of operating environment
•
Influence of static pressure
-0.009dB/kPa (for 1kHz)
•
Influence of temperature
≤
±
0.7dB (for 1kHz)
•
Influence of humidity
≤
±
0.1dB (without condensation)
•
Influence of electromagnetic field
conformable to EN 61672-1:2003
specifications (maximum when
meter 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
not detectable
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 windscreen (at 0
°
incidence)
See table below and Fig. 1.5.
f [Hz]
250
315
400
500
630
800
1000
1250
1600
2000
2240
dL [dB]
0.07
0.12
0.13
0.12
0.16
0.27
0.24
0.34
0.47
0.45
0.53
U [dB]
≤
0.08
≤
0.10
f [Hz]
2500
2800
3150
3550
4000
4500
5000
5600
6300
7100
8000
dL [dB]
0.47
0.49
0.50
0.49
0.21
0.18
-0.08
-0.15
-0.25
0.34
-0.35
U [dB]
≤
0.10
f [Hz]
8500
9000
9500 10000 10600 11200 11800 12500 13200 14000 15000
dL [dB]
-0.06
-0.37
-0.54
-0.40
-0.84
-0.32
-0.98
-0.69
-2.09
-1.56
-1.74
U [dB]
≤
0.10
≤
0.11
