Otoacoustic Emissions & Auditory Brainstem Response Flashcards Preview

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Flashcards in Otoacoustic Emissions & Auditory Brainstem Response Deck (11):
1

2 Jobs of Outer Hair Cells

1. Amplify traveling wave for sounds (

2

Spontaneous Otoacoustic Emissions (SOAEs)

Sounds produced by the cochlea in absence of input

3

Distortion Product OAE

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*

4

If OHC damage will see ________ in audiogram

High frequency noise notch

5

Auditory Brainstem Response

Automatic, early latency response (10-15 ms of stimulus)
Tests inner hair cells & brainstem NOT HEARING

6

ABR Waves

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

7

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

I , III , V
V to get ABR Threshold

8

Clicks
Tone bursts

Response from 2000-4000 Hz
Response w/in given Hz range

9

Info obtained from each ear doing ABR:

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

10

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

If increases a lot = abnormal

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

11

Retrocochlear Lesions (Tumours, MS)

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