1. Equipment for measuring OAE
Depends on the type of OAE.
For SOAE: Probe with tiny sensitive microphone
For TEOAE: Probe with miniature loudspeaker to present the click or tone burst, and a microphone to pick up emissions
For DPOAE: Probe containing two loudspeakers and a microphone 1

2. OAE Diagnostic value Very useful in difficult-to-test populations.
If emissions are present:
Conductive pathway is normal.
The particular region of the cochlea is normal.
If emissions are present in case of SN hearing loss:
Problem not in OHC, but in regions beyond the cochlea (retrocochlear)
If emissions are absent in case of SN hearing loss:
Problem in cochlea (OHC), but could also be retrocochlear problems. 2

3. Auditory evoked potentials
Electrical responses that occur in the cochlea and auditory pathways in response to sound.
Measured by presenting a series of sounds through transducers.
Responses picked up by electrodes placed at various locations.
Responses averaged to remove noise.
Terms:
Latency: Time between introduction of stimulus and the occurrence of the response. Depends on the part of the auditory system that generates the response.
Amplitude: The strength of the measured response. 3

4. ABR Early responses (10-15 ms latency).
Originate from the eighth nerve and brainstem.
Present a series of clicks or tone-bursts.
Measure responses in a graphical form (waveform).
Each part of the waveform thought to arise from a specific part of the auditory pathway. 4

5. Probable sites of origin (Møller, 1985)
Wave number
Site of generation I
VIIIth nerve II
III
Pons IV V
Midbrain
VI and VII ?? 5

6. Normal ABR 6