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0611 RM500SL User’s Guide Version 2.8 Page 35
7.10 Calibration check for coupler microphone
FastFacts 7.10: Calibration check for coupler microphone
Accuracy of HIT measurements depends on the calibration of the coupler
microphone. This should be checked regularly using a microphone calibrator with
an adapter ring. The RE780 (1 1/8”) and RE781 (1”) rings are designed for Quest
CA22 and QC-10/20 respectively. To verify the coupler microphone calibration:
1) Calibrate the HIT reference microphone. See 7.9: Calibration of HIT reference
microphone
2) Screw the appropriate calibrator ring onto the coupler microphone.
3) Insert the coupler microphone with the attached calibrator ring into the
calibrator opening.
4) Turn the calibrator on and adjust it to present one of the available frequencies
and levels (e.g., 94 dB SPL at 1000 Hz).
5) Press <Tests>, then highlight and <PICK> HIT [Manual control].
6) Highlight and <PICK> the [Level] window, then highlight and <PICK> 0 from
the drop-down list.
7)
Highlight, then <PICK> the [Frequency] window, then highlight and <PICK> the
frequency of the calibrator (e.g. 1000 Hz) from the drop-down list.
8) Highlight, then <PICK> the [Filter] window, then highlight and <PICK> 1/12th
octave from the drop-down list.
9) Highlight, then <PICK> [Start test] (which changes to [Stop test]).
10) Check that the Coupler microphone level is within 1 dB of the calibrator level
setting, +/- the calibrator accuracy. For a 94 dB calibrator with +/- 0.3 dB
accuracy, the indicated coupler microphone level should be 94 +/- 1.3 dB.
11) To stop the measurement, highlight and <PICK> [Stop test].