Svantek SV 977D - Page 241

241
SV 977D User Manual - Appendixes
Special filters
• Diffuse Field compensation filter that improves the complete instrument
frequency response in the diffuse acoustic field (see below)
• Windscreen compensation filter that improves the instrument frequency
response in the free acoustic field when the SA22 windscreen is
mounted on the microphone (see Chapter C.1.2)
SV 977D Diffuse Field compensation filter
Note: Using special filters might change the frequency response and measuring ranges of SV 977D.
Please check the below given specification.
Linear operating ranges for LEQ measurements with the Diffuse Field filter
The starting point at which tests of level linearity shall begin is 94.0 dB for the frequencies specifies below. For
the Low measurement range and A weighting linearity test at 31.5 Hz, the starting point is 74 dB.
Table C.1.2. Linear operating ranges for the Low measurement range with the Diffuse Field filter (for the
sinusoidal signal and microphone sensitivity 50 mV/Pa)
[dB]
L
AS/F
L
BS/F
L
CS/F
L
ZS/F
L
AeqT
L
BeqT
L
CeqT
L
AE
L
Cpeak
(t
int
= 2 s)
from
to
from
to
from
to
from
to
from
to
from
to
from
to
from
to
from
to
31.5 Hz
24
80
26
103
26
117
32
120
24
80
26
103
26
117
27
83
51
120
500 Hz
24
116
26
119
26
120
32
120
24
116
26
119
26
120
27
119
51
123
1 kHz
24
120
26
120
26
120
32
120
24
120
26
120
26
120
27
123
51
123
4 kHz
24
121
26
119
26
119
32
120
24
121
26
119
26
119
27
124
51
123
8 kHz
24
119
26
117
26
117
32
120
24
119
26
117
26
117
27
123
51
120
12.5 kHz
24
115
26
114
26
114
32
120
24
115
26
114
26
114
27
118
51
117