HP RM500SL - Manual (Page 33)

0611 RM500SL User’s Guide Version 2.8 Page 33
7.8 HIT calibration facts
FastFacts 7.8: HIT calibration facts
HIT microphone calibration establishes a correction curve for the uncalibrated HIT
reference microphone by comparison with the factory calibrated coupler
microphone. It may be performed as often as desired but will be invalidated at 1
am the following day or at 1 am the following Monday, depending on the choice of
Daily or Weekly calibration interval. After the calibration has expired, you will be
prompted to calibrate whenever you attempt a test that uses the HIT microphones.
Note that there are two styles of HIT reference microphones. The newer style is
larger but responds beyond 16 kHz and has a lower noise floor. The two have
different correction curves, as shown below, but will produce the same test results,
once calibrated. Your calibration curve should be similar to one of these and
should remain stable over time. Irregularities in the calibration curve may be the
result of positioning errors. See
7.9: Calibration of HIT reference microphone.