HP RM500SL manual Calibration check for coupler microphone

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].

FastFacts 7.10: Calibration check for coupler microphone

0611 RM500SL User’s Guide Version 2.8 Page 35