Audioscan Verifit 2 - Manual (Page 96)

Verifit ® User's Guide Version 4.2 © June 2015
curve. Any change in this curve indicates a drift in either the coupler or the reference microphone which needs
further investigation. See Calibration check for coupler microphone for an additional check.
Calibration check for coupler microphone
Accuracy of test box 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 in.) and RE781 (1in.)
rings are designed for Quest CA22 and QC-10/20 respectively. To verify the coupler microphone calibration:
1. Calibrate the test box reference microphone. See Calibrating test box 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. Right-click the mouse and click [Manual control] under Test box.
6. Click the [Level] window, then select 0 from the drop-down list.
7. Click the [Frequency] window, then select the frequency of the calibrator (e.g. 1000 Hz) from the drop-down
list.
8. Click the [Filter] window, then select 1/12th octave from the drop-down list.
9. Click [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, click [Stop test].
Coupling for binaural/wideband tests
For non-ANSI test-box tests (e.g. Test box Speechmap) the two 0.4 cc wideband couplers must be used. The
binaural coupler microphone is coded with a red and blue side for right and left ear respectively.
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