Interacoustics AS608, Operation Manual

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AS608/AS608e Operation Manual Page8 Page 8
Operation Manual
Familiarization:
Present a tone at 1000 Hz which can easily be perceived
(i.e. 50dB) If necessary, increase with steps of 10 dB until
the tone is clearly perceived.
Threshold Determination:
The hearing threshold is defined as the lowest level at
which more than half of the stimuli are heard. This
threshold is found by the following procedure.
1)
Present a tone which is 10 dB lower than the level at
which familiarization was finished.
2) Decrease the level in steps of 10 dB until response
fails.
3) Increase the level in steps of 5 dB until the subject
responds again.
4) Repeat 2) and 3) two or three times until the threshold
appears at the same level.
The time intervals in between the stimuli should be varied
to prevent the subject to react on the rhythm.
5)
Change to the next frequency and repeat the
procedure until all frequencies are measured. Repeat
the procedure at 1000 Hz. If the difference to the
previously found threshold is then 5dB or less go to
the other ear. If the difference is 10 dB or higher,
repeat the test at the other frequencies, until
agreement to 5 dB or less has been obtained.
6) Proceed until both ears have been tested.
Screening Procedure:
It is common to test at one dB level for preliminary hearing
screenings as is often done in schools and primary practice clinics.
In this instance you would follow the same familiarization and
instruction procedures as stated above, but present a single dB level
(i.e. 25dB) at just 4 frequencies (500, 1000, 2000 & 4000 Hz) in each
ear. In this instance, you simply record a response or no response to
the single tone presentations at each frequency.