6
LI0107 - Revision 7 September 2012
Fig 2.2
Pistonphone fitted with Coupler RA0090 and the microphone inserted into the coupler. The spring arrange-
ment supplied with the coupler is not used.
6. Mount the microphone of the Type 40HL in the Coupler as shown in Fig. 2.2, and switch the
Pistonphone on.
7. Adjust the analyzer to indicate 94 dB* re. 20 μPa.
Frequency Response Calibration
The frequency response of the microphone has been factory-calibrated in a free field (anechoic
chamber) by comparison with a reference microphone.
* Plus any corrections for barometric pressure. See pistonphone manual.
