Grason-Stadler GSI
®
61 CLINICAL AUDIOMETER
Distortion and Frequency Shift
This check can be made by listening to the GSI 61’s output through the earphones and
pressing all frequencies (in the 125 Hz to 12000 Hz range) at a loud, but not uncomfortable level
(70 to 80 dB HL for normal ears). Listen also to ensure that the signal frequencies change
appropriately when the FrequencyL and R pushbuttons are operated. If distortion is heard
in one earphone but not the other, the chances are high that the earphones are at fault and
should be replaced. In any case, the audiometer should be scheduled for immediate
maintenance.
Speech Level Check
To check the speech level with recorded speech, select Ext. A, Channel 1, and ensure an external
CD player is plugged into the GSI 61. Place the earphones on a person with normal hearing –
Less than 25 dB. Present a word list from the CD player at 40 dB. If intelligible speech is not
heard with the Channel 1Hearing Level control set at 40 dB or less, the audiometer or the
external device should be scheduled for technical service. To double check a possible problem
with the audiometer, check the speech level with live voice through the Mic.
Internal Controls Check
Should the front panel controls lock into one state and it is not possible to change any of the
parameters, turn off the power. Wait one minute and then power on.
Bone Vibrator Check
This check must be performed in a quiet environment or in a sound room. With the frequency Hz
set to 2000 Hz, the Channel 1 HL set at 40 dB HL and the bone vibrator positioned properly, the
tone should be clearly audible to a person with normal hearing – less than 25 dB. When a
bone vibrator fails this test, the calibration should be verified. If the bone vibrator cannot be
calibrated to specifications, it should be replaced.
Masking Level Check
Select the Tone test type. Activate the Channel 2 Interrupt button so that it is on. Listen for
a smooth, even hiss with the Channel 2 Hearing Level control set at 50 dB HL.
Talk Forward Check
Speech should be clearly audible (in the earphones) when spoken in a normal tone with the
Talk Forward dB HL control set at 45 dB HL.
5-2
1761-0100 Rev. B
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