Otoacoustic Emissions & Auditory Brainstem Response

Question 1

2 Jobs of Outer Hair Cells

Answer 1

1. Amplify traveling wave for sounds (

Question 2

Spontaneous Otoacoustic Emissions (SOAEs)

Answer 2

Sounds produced by the cochlea in absence of input

Question 3

Distortion Product OAE

Answer 3

2f1-f2 frequency = largest in mammals
Measured in amplitude
DP-Grams mimic audiograms
SNR >5-6 dB
*WILL NOT BE THERE IF HL >50 dB*

Question 4

If OHC damage will see ________ in audiogram

Answer 4

High frequency noise notch

Question 5

Auditory Brainstem Response

Answer 5

Automatic, early latency response (10-15 ms of stimulus)

Tests inner hair cells & brainstem NOT HEARING

Question 6

ABR Waves

Answer 6

I - Cochlea & 8th CN
II - 8th CN
III - Pons
IV - Pons
V - Midbrain

Question 7

At high intensities (70 dB HL) clear responses should be seen for waves _ , _ & _.
Then decrease until wave _ is undetected to get ______________.

Answer 7

I , III , V

V to get ABR Threshold

Question 8

Clicks

Tone bursts

Answer 8

Response from 2000-4000 Hz

Response w/in given Hz range

Question 9

Info obtained from each ear doing ABR:

Answer 9

Absolute latencies of all waves @ different intensities
Interpeak intervals (I to V, I to III, III to V)
Wave amplitudes (absolute and relative)
Threshold of wave V

Question 10

Interpreting ABR:
As you near threshold wave V increases slightly (normal)
Conductive HL:
SNHL:

Answer 10

If increases a lot = abnormal

Conductive: elevates threshold (by AIR), slows all waves equally
SNHL: Prolong/elevate wave V threshold

Question 11

Retrocochlear Lesions (Tumours, MS)

Answer 11

Prolong interpeak intervals
Wave V latency significantly different b/t ears
Amplitude ratios abnormal (normally V is bigger than I)
Wave V abnormally prolonged w/ high click rate