Operating Instructions MA 42
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5.2 Speech Audiometry
The MA 42 supports speech audiometry. To conduct speech tests using speech
test material you can use a CD player, wave files from SD memory card, or a
microphone. The gooseneck microphone can be used for live speech
audiometry and communication with the patient.
Caution: If you are using a CD player powered by electrical current, the
player must meet electrical safety requirements, such as IEC 601-1 or
UL. This is to avoid electrical shock of either the patient or you. If you
are not sure if your player meets these requirements it is safer to use
battery power.
5.2.1 Input Calibration
The MA 42 must be calibrated to the particular speech test to ensure valid test
levels. That means every time you change the speech test CD you must
recalibrate the instrument.
To calibrate the CD speech input select CD with the signal selector key (11),
(15). Press the Monitor button (6) and then InCal (19) and the calibration screen
appears.
On every CD with speech test material you have a reference signal, such as a
reference tone or speech simulating noise. Play back the reference signal with
CD. Use the left or right level control (1) and adjust the levels until the VU-
meter (21) shows all yellow and one green light.
If one or more red lights are on, reduce the level using the corresponding dials
(1).
To calibrate the microphone for live voice testing, select MIC with the SIGNAL
selector key (11), (15). Press the Monitor button (6) and then InCal (19) and the
calibration screen appears. Use the left or right level control (1) and adjust the
levels until the VU-meter (21) shows all yellow and one green light.
Figure 10 - Input Calibration
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