Performing A Teaoe Measurement; Probe Check; Rejection Level; Start The Test - Interacoustics Eclipse Additional Information

Eclipse Additional Information
9.7

Performing a TEAOE measurement

9.7.1 Probe Check

There are a number of factors that can affect the measurement of TEOAEs. These include the type of stimu-
lus used, the noise floor or the amount of ambient and physiologic noise present during the testing (Rhoades
et al, 1998), and; the position of the probe within the ear canal.
1. Select the ear that will be measured (Left/Right).
2. It is also recommended to first check the stimulus characteristics in the ear canal before testing. This is
done by pressing the probe check button and monitoring the two graphs in the upper left corner of the
screen.
A relatively flat FFT and a peaked response with little ringing is the desired probe check response. When an
appropriate probe check has been found, then a green light will appear at the bottom right of screen. If an
optimum fit has not been achieved at the place where the grey line intercepts the probe check display then a
red light will appear at the bottom right of screen. If this occurs the probe should be manipulated within the
ear canal until a more satisfactory response is found. Further guidelines for fitting the probe are given in
Kemp et al., 1990.

9.7.2 Rejection level

The level of the noise floor must also be monitored before a recording can be made. The noise floor can af-
fect the recording and the amplitude of the emission. If you are using the TEOAE25 in a test environment
with a high level of ambient noise and a noisy patient, it will be necessary to increase the rejection level by
dragging on the slide bar. In such a case you will notice that an 'Overload' warning is given over the 'Rejec-
tion Level (dB)' display.
Satisfactory results are unlikely in circumstances of high ambient or patient noise and it is always preferable
to eliminate or reduce the noise rather than increase the rejection level. If you are recording from a relatively
quiet patient in sound treated surroundings, the Rejection Level can be reduced by dragging the slide bar to
the left.

9.7.3 Start the test

Once the desired stimulus characteristics have been obtained the recording of the OAE measurement can
be initiated by pressing the Start button. When the test is complete the results will be shown in the TE re-
sponse window. The way the data is shown depends on the selected protocol and the display settings of the
protocol. Below are examples of TEOAE measurements for a Clinical test and for a Pass/refer test.
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