OAEs

Question 1

What are OAEs?

Answer 1

Sounds generated in the inner ear travel through the middle ear and into the ear canal where they can be measured by miniature microphone
They arrive in the ear canal because the middle ear receives vibrations from deep inside the cochlea
This causes the eardrum to vibrate the air in the ear canal creating the sounds that we can record

Question 2

Do OAEs reflect the condition of the OHCs?

Answer 2

Yes
Healthy OHCs produced robust OAEs, while damaged OHCs led to reduced or absent OAEs
Lesions to other parts of the cochlea and/or central auditory system did not result in absent OAEs, when cochlear OHCs are intact

Question 3

Are OAEs believed to be a byproduct of the cochlear amplifier?

Answer 3

Yes
OAEs arise because some of the energy generated by outer hair cells leaks back into the ear canal

Question 4

Are spontaneous OAEs often reported to be more prevalent in newborns?

Answer 4

Yes
DPOAEs are also present in nearly all normal-hearing newborns and children
In newborn and children, OAEs are higher in level than adult OAEs

Question 5

When do DPOAE levels peak?

Answer 5

Halfway through the first year of life
Level gradually decrease with age, but they remain slightly higher than adult levels throughout childhood

Question 6

What do OAEs tell us about auditory function?

Answer 6

Normal OAE amplitudes provide evidence that outer hair cells for that portion of the cochlea are intact
Normal OAEs also indirectly indicate that a patient’s middle ear is functioning normally
Decreased OAE amplitudes or absence of detectable DPs for test frequencies are evidence of cochlear dysfunction involving outer hair cells

Question 7

Is a proper probe fit essential for good OAE recordings?

Answer 7

Yes
The probe tip should be appropriately sized and securely seated on the probe
The probe should be properly inserted into the ear and stay secure and stable without support
The correct size tip will look slightly larger than the ear canal and should fit snugly

Question 8

How can you reduce OAE recording time?

Answer 8

By not testing the low frequencies

Question 8

What are the most frequent causes of unsuccessful OAE recordings?

Answer 8

Failure to fit the probe correctly, so that it is deep enough in the ear canal
Conductive elements (fluid/debris)
Babies are restless

Question 9

What are some diagnostic applications of OAEs?

Answer 9

Newborn hearing screening.
School screenings
Site of lesion testing (cochlear vs retrocochlear basis)
Monitoring of effect of ototoxic drugs on cochlear function
Partially estimate hearing sensitivity within a limited range
Cross check principle

Question 10

In difficult to test children, can OAEs be used to quickly indicate the need for further intervention?

Answer 10

Normal OAEs, tympanograms, and acoustic reflexes generally rule out peripheral hearing loss
Absent or abnormal OAEs and normal tympanogram indicate the need for further evaluation

Question 11

What are the types of OAEs?

Answer 11

Spontaneous
Sustained frequency (SFOAEs)
Transient evoked (TEOAEs)
Distortion product (DPOAEs)

Question 12

When are TEOAEs used?

Answer 12

Commonly used to screen infant hearing
To validate behavioral or electrophysiologic auditory thresholds
To assess cochlear function relative to the site of lesion

Question 13

What is the stimulus used for TEOAEs?

Answer 13

Very short or transient stimuli
Click or tone burst

Question 14

When are TEOAEs absent?

Answer 14

Once hearing exceeds 30 dB HL

Question 15

What are DPOAEs?

Answer 15

Evoked responses from two simultaneously presented pure tones (different level and freq)

Question 16

What frequency does the most robust DP occur at?

Answer 16

2f1-f2

Question 17

What frequency range are DPOAEs attainable at?

Answer 17

500 to 8000 Hz

Question 18

What do you have to examine on otoacoustic emissions to ensure that they are valid?

Answer 18

Stimulus graph
Probe graph
Noise floor
OAE level

Question 19

Do DPOAEs and TEOAEs provide the same information?

Answer 19

No
They may target different cochlear mechanisms
Including both types can provide a more comprehensive assessment of cochlear health and hearing loss

Question 20

What should you do if DPOAEs are not initially detectable at the standard stimulus levels (65-55 dB SPL)?

Answer 20

Use higher stimulus levels (75-65 dB SPL)
May reveal hearing loss that is not profound

Question 21

Can the ME effect OAEs?

Answer 21

Yes, the OAEs have to pass through the ME to be measured
Otitis media or negative pressure can disrupt sound transmission to and from the cochlea, altering OAE measurements
Severe otitis media can affect mobility of the TM and OAEs are likely to be absent
Negative ME pressure typically reduces OAE levels, but may not be absent
PE tubes and perfs can result in variable measurements

Question 22

What are some limitations of OAEs?

Answer 22

Susceptible to noise
Site specificity
Cannot quantify degree of HL
Cannot rule out minimal or mild HL

Question 23

What are the advantages of OAEs?

Answer 23

They evaluate OHC function
They are quick and objective
They are ear specific
They are frequency specific
Can predict future hearing loss, allowing for early intervention and preventive counseling
No booth is required