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)