CHAPTER TEN
DPOAE test
94
The stimulus spectrum should be a smooth, rounded curve. A jagged
stimulus response in the low frequencies or a sharp peak in the mid-
frequency range indicates a poor probe fit. Dips in the stimulus spectrum
may be caused by standing waves in the ear canal. A dip indicates a drop
in intensity at the probe microphone but may not necessarily indicate a dip
in the stimulus intensity at the eardrum. Longer adult ear canals are more
likely to show these standing wave effects.
Stimulus spectrum
is very sensitive to probe fit. This can make it a useful
tool for checking continuity of fit over separate testing sessions.
The stimulus spectrum for channel A is displayed in white while channel
B is displayed in blue. Significant differences between the two spectrums
may be caused by poor probe fit, probe blockages or probe faults.
10.2.4
Test condition information
Checkfit OK
will appear at the top of the screen if the adjusted stimulus
level is correct and the noise is consistently below the reject level.
Noisy
appears if high noise conditions cause the shaded noise bar to be
consistently above the reject level for a period of time.
Check Probe Fit
is shown if the adjusted stimulus level falls outside the
accepted stimulus range or if the stimulus levels of the two channels are
more than 2dB different.
When
Checkfit OK
is present on screen indicating conditions are suitable
for testing, select
Start
to begin a test or
Cancel
at any point in
Checkfit
to
return to
Patient Details
.
Stim out of Range
will appear if
Start
is selected when the stimulus is
outside the accepted range. It is advisable to select
Back
to return to
Checkfit
and readjust. Select
Continue
to start the test anyway.
Additional checks on testing conditions are the stimulus (
S
) and noise (
N
)
indicators (above the screen). Both LEDs are lit in ideal testing conditions.
DPOAE test
Summary of Contents for Otoport Advance
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