COSD 330: Introduction to Audiology
Acoustic Reflexes, Otoacoustic Emissions, and ABR
Acoustic Reflexes
Stimulus probe &
measurement probe in
same ear
Stimulus probe &
measurement probe in
same ear
Stimulus probe
Measurement probe
Stimulus probe

Measurement probe
What is the acoustic reflex response? Response of the stapedius muscle to sound
o What information does it provide? Function the nervous system (up to the level of the
SOC), status of the middle ear, and the site of lesion (where the pathology might exist)
o What is the acoustic reflex threshold (ART)? Determined to be the minimum amount of
change in compliance needed to elicit the reflex (typically 0.02 mmho)
 How is the acoustic reflex threshold recorded? Ipsilaterally and contralaterally,
 ipsilaterally, probe tone and reflex measured in the same ear,
 Contralateral= probe tone presented to one ear, reflex measures in opposite ear
 Where is the probe tone and the measurement probe for an ipsilateral
reflex? In the same ear
 Where is the probe tone and the measurement probe for a contralateral
reflex? Right contralateral, probe is presented in right ear, measuring
the reflex in the left.
o 500,1000,2000
o At what dB are acoustic reflexes are obtained in the normal hearing population? 70100dB
o What is the procedure for obtaining acoustic reflex thresholds (ARTs)?


Present a starting tone at 90dB
ART is present if a value of at least 0.02mmho (without getting lower) is obtained
at a certain intensity

I is for ipsilateral at 500Hz
What is the acoustic reflex threshold? Provide your rational.
The acoustic reflex threshold is 85dB HL, because the change in compliance (.04mmho) was as close to
.02mmho without going under.
o How is the acoustic reflex interpreted?
 What are the afferent (peripheral to central) portions of the reflex arc? Up. any of
the relay station going up. include middle ear, cochlea, 8 cranial nerve, cochlear
nucleus, and the SOC
 What are the efferent (central to peripheral) portions of the reflex arc? Down.
Include Cranial nerve 7 and the stapedius muscle
 If both portions of the reflex arc are intact, the acoustic reflexes will be present
 3 principles regarding absent acoustic reflexes 1 conductive component like ear infection will cause no acoustic reflex’s
 2 if HL greater than 80dB, profound hearing loss, no reflex, not able to go loud
enough to elicit a response.
 3 if there is a pathology to the cranial nerves, I will also have absent reflex’s,
sound will be blocked or stopped at that level
Otoacoustic Emissions (OAEs)
 How are OAEs defined?
o What is it a measure of?

What are the 2 types of OAEs and how are they elicited?

What are the pitfalls of OAEs?

What are the advantages to OAEs?
Auditory Brainstem Response (ABR) Testing
 What are ABRs considered?
o Various tests in the evoked potential test battery differ in the latency in which the
potentials appear
 What is latency and what does it reflect?

What are the two broad classifications of ABR?

ABR Test Procedure
o Need to control for unnecessary movements; therefore, it is encouraged that the patient
take a nap during testing
 Young children and individuals with disabilities need to be sedated
o Record evoked potentials – displayed as waveforms where wave morphology is
assessed and waves corresponding to areas along the auditory system are identified
 Wave I =
 Wave III =
 Wave V =

General rules for interpretation
o Wave I is often delayed if:
o Waves I-V are often delayed if:
o Only Waves III and V are delayed in cases of :