Operating Instructions MA 42
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5.1.7 The Threshold Decay (Carhart) Test
This examination is conducted as a fatigue test in cases of sensitivity loss.
To start the test select Decay with the functional selector button (13), choose
OT Tests and Decay Test. Make sure that the correct transducer is selected in
advance.
Select left or right ear (9) and the test frequency with the frequency keys (4),
(5).
Adjust the test level with the intensity control dial (1). The level should be set
to a value 5 dB above the individual pure tone hearing threshold at this
frequency.
Instruct the patient to hold the response switch while the tone is heard and to
release the switch as soon as the tone is not heard anymore.
Press START (19) to begin the test and present the test signal to the patient.
The patient response LED lights and a stopwatch counts the seconds as long as
the patient response switch is pressed. As soon as the patient releases the
response switch, the level is increased for 5 dB.
The test stops automatically if the patient is able to hear the tone at the same
level for 60 seconds or if the level is increased for 30 dB. Press STOP (18) to
terminate the test before.
Figure 7 Start Screen Decay Test
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