acoustic reflexes - exam 2

Question 1

what are we measuring for acoustic reflexes

Answer 1

a change in energy flowing through the middle ear when a loud sound triggers the acoustic reflex

Question 2

what is an acoustic reflex

Answer 2

the contraction of the middle ear muscles in response to loud sounds

primarily involves stapedius muscle
attached to neck of staples, innervated by VNII (facial nerve)

Question 3

increased stiffness leads to a/an ______ in acoustic admittance

Answer 3

decrease

Question 4

We measure a change in ________ to assess if there was a reflex

Answer 4

admittance

Question 5

acoustic reflex threshold

Answer 5

lowest level at which the AR occurs

usually assess here

Question 6

AR symmetry

Answer 6

reflex is always bilateral

occurs in both ears regardless of where the sound is presented

Question 7

ipsilateral reflex pathwaty

Answer 7

middle ear –> cochlea –> middle ear

Question 8

contralateral reflex pathway

Answer 8

middle ear –> cochlea –> other middle ear

Question 9

ipsilateral reflexes mean that reflex is measured in the _____ (same/opposite)
ear that is stimulated

Answer 9

same

Question 10

Contralateral reflexes mean that reflex is measured in the _____ (same/opposite)
ear that is stimulated

Answer 10

opposite

Question 11

What ear do we use to specify side?

For example, right contralateral
means what (stimulus or reflex measurement) is on the right side

Answer 11

stimulus

reflex on the left

Question 12

acoustic reflex stimulus

Answer 12

pure tones most commonly, 1 sec

Question 13

AR freqs tested

Answer 13

500, 1000, 2000, & 4000 Hz

lower freqs more common

ARTs freq dependent - can have normal reflexes at some but not others

Question 14

AR levels

Answer 14

start at 80 dB HL & increase in 5 dB steps until a response is seen or max limit reached

do not exceed 105-110 dB HL – too loud

Question 15

possible ART outcomes

Answer 15

present at normal levels:
<= 95 dB HL

present at elevated levels:
100-110 dB HL

absent:
not present at 105/110 dB HL

Question 16

sensorineural hearing loss reflexes

Answer 16

issue in inner ear

hearing thresholds 0-55 dB HL –> normal

55-70 –> elevated

> 70 –> absent

Question 17

conductive hearing loss reflexes

Answer 17

issue in middle ear
mixed hits conductive first

mild conductive hearing loss 25-41 –> absent or elevated

> mild –> absent

Question 18

acoustic reflex decay

Answer 18

measures if reflex contraction is maintained or diminished during continuous stimulation

decay occurs because stapedius muscles fatigues

faster than normal decay = retrocochlear (neural Pathology)

Question 19

AR decay procedure

Answer 19

freqs: 500/1000 Hz

level: 10 dB above ART

duration: 10 secs

Question 20

normal delay

Answer 20

contraction continues as long as stimulus is on

Question 21

abnormal delay

Answer 21

contraction stops before stimulus is off

> 50% decay