CHAPTER TWENTY-SIX
Mode of operation
194
Mode of operation
26.2
TEOAE test
Parameter
Description
Stimulus
Idle
80µs positive broadband square wave pulse with an intensity of
64dB pe (peak equivalent) in a 1cc cavity.
Adjusted
80µs positive broadband square wave.
Test
300µs biphasic broadband triangular pulse.
Sample rate
20kHz
Stimulus pattern
Each sweep presents 8 stimuli responses with the stimulus
presentation pattern:
A A A B -A -A -A -B
Where: B = -3A
Noise rejection calculation
The noise level for noise reject is calculated from
the difference
between consecutive sweeps.
Averaging
The responses from each stimuli in a sweep are summed and
averaged.
Averaging this stimulus pattern removes artefacts which scale
linearly leaving only the OAE signal which is non linear.
These sub averages are alternately added to two separate
averages. These separate averages are referred to as
waveforms A and B.