OAEs Flashcards
Typically takes much less time
screening
Fewer frequencies assessed, usually higher frequencies
screening
A component of a comprehensive test battery
diagnostic
Requires interpretation from audiologist
diagnostic
Completed to distinguish those who do not have significant auditory dysfunction from those who need further evaluation
screening
OAE outcomes will always fall within one (1) of three (3) general categories. Which of the following are those three (3) categories?
OAE amplitude is normal (relative to normative data)
Amplitude is abnormal, but OAEs are present
The noise floor is less than the amplitude of the response
The noise floor is equal to the amplitude of the response
OAEs are absent
OAE amplitude is normal (relative to normative data)
Amplitude is abnormal, but OAEs are present
OAEs are absent
The most important contributor to OAE production is the motility of the outer hair cells. Please elaborate on this idea, explaining how they produce OAEs (from stimulus delivery to recording).
The stimulus is presented into the external auditory canal. It then passes through the tympanic membrane into the middle ear where it acts as an impedance matcher through the ratio size between the tympanic membrane and the stapes footplate in the oval window, the lever action of the ossicles, and the buckling of the tympanic membrane. Once the stapes footplate pushes into the oval window into the fluid in the cochlea, this creates a travelling wave. This traveling wave reaches the part of the basilar membrane that is most susceptible to movement from the frequency of the original stimulus wave. Once the basilar is displaced to its maximum displacement, the stereocilia on the outer hair cells are sheared, causing potassium ions to rush in, activating calcium ion channels to open and let calcium in. This rushing in of ions causes the outer hair cells to elongate and shorten, which is the electromotility. This electromotility of the outer hair cells produces OAEs. The OAEs that is produced from the outer hair cell travels back out of the oval window at the stapes footplate as a reverse wave. This then pushes through the middle ear losing its amplitude because the mechanisms that acted as impedance matchers are now impedance mismatchers and cause the spiked heel effect on the OAE. The OAE then reaches the tympanic membrane and back out to the external auditory canal to be measured and picked up by the probe.
Generally speaking, slight middle ear disorders that may not entirely obscure OAEs affect responses first for the lower frequencies.
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Please list for me three (3) non-pathological ear canal factors that can affect OAE measurement. One of them must be standing waves
1) age
2) women
3) in proper probe placement
What role(s) does the external auditory meatus (or canal) play in OAE measurement?
both inwaard and outward propagation
In collection of TEOAE responses, the No. Hi. (number of rejected samples) refers to the number of runs that were rejected because the incoming noise peaks exceed the Rejection Level in dB SPL.
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Which medical red flags contraindicate the recording of OAE responses?
Active drainage in the ear canal
A foreign body in the ear canal
A history of middle ear dysfunction
Active bleeding in the ear canal
Active drainage in the ear canal
A foreign body in the ear canal
Active bleeding in the ear canal
The amplitude of OAE responses are typically larger with greater reproducibility in adults when compared to children and infants.
f
In ears with a perforation or a patent ventilation tube, which of the following is true?
OAE responses will always be absent in ears with tympanic membrane perforation or ventilation tube.
OAE responses will always be present in ears with tympanic membrane perforation or ventilation tube.
Tympanic membrane perforation and ventilation tubes are medical red flags and OAE testing should not be attempted.
Present OAE, absent OAE, partial OAE, or reduced amplitude OAE responses may be observed in dry ears with tympanic membrane perforation or ventilation tubes.
Present OAE, absent OAE, partial OAE, or reduced amplitude OAE responses may be observed in dry ears with tympanic membrane perforation or ventilation tubes.
What are the two (2) pure tones labeled as in DPOAE parameters?
f1 and f2
What are the two (2) pure tones labeled as in DPOAE parameters?
When recording DPOAEs, we input two pure tones, and receive a third tone which we measure as the response from the cochlea. What do we call that produced, third tone?
The distortion product
The frequency relationship or separation between the two (2) primary tones is critical in DPOAE measurement. A DP will not be recorded if the two (2) tones are too far apart or if they are too close together.
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With regard to f1 and f2, what is the most reliable frequency relationship of these two (2) primary tones? Please provide the number that expresses what that ratio should be.
F2 is the most reliable frequency of the two
The ratio should be 1.22
The relative levels (intensity) of the two (2) primary tones (L1 and L2) is another critical stimulus parameter in DPOAE measurement. To obtain results most sensitive to cochlear function, what should L1 and L2 be in intensity?
65 and 55 dB SPL
What are the four regions of the auditory system that either contribute to the generation of OAEs, or can influence OAE recording?
Outer ear,
middle ear,
inner ear,
efferent system
Please explain the Crosscheck Principle and include an example.
using electro-physiological or electroacoustical tests to confirm a subjective test (like pure tones)
ex: if you get absent or abnormal OAE’s you do not diagnose a HL, OAE are not a test of hearing you would use the information collected by the OAE to run a audiologic evaluation and then compare and see if it supports or does not support your original findings.
How is a DPOAE determined to meet passing criteria?
The absolute amplitude of the DP should be at least -20 dB SPL
The DP-NF (the SNR) should be at least 10 dB SPL
Passing responses should be seen in 1 frequency
None of these responses are correct
None of these responses are correct
Why should we NOT use intensity levels in DPOAE testing (L1 and L2) that are over approximately 70-75 dB SPL? For example, if we do use high intensity levels, and we get a response, how does that relate to cochlear function?
The reason for that is now you are using passive cochlea processing. With a higher db you are by passing the outer hair cells and stimulating the inner hair cells. when you do this you may vibrate the basilar membrane but you are not measuring the correct outer hair cell motility. meaning you are not getting an accurate representation of outer hair cell and cochlear function.
There is now considerable evidence that noise- or music-induced cochlear damage is detectable with OAEs before it becomes apparent in the audiogram
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Which of the following best describe the clinical applications of OAEs for adults? Please choose all that apply.
Monitoring tinnitus and noise or music exposure
Differentiation of cochlear vs. retrocochlear site of lesion
Newborn hearing screenings
Monitoring hyperbilirubinemia
Assessment in suspected functional hearing loss
Monitoring tinnitus and noise or music exposure
Differentiation of cochlear vs. retrocochlear site of lesion
Assessment in suspected functional hearing loss
What is a Gorgagram?
A version of a DP gram with normative values from the 5th percentile to the 95th percentile used to indicate if hearing is normal, abnormal or borderline.
A version of a DP gram with normative values from the 5th percentile to the 90th percentile and tells us about auditory processing.
An audiogram created by MIchael Gorga, Ph.D. that is only used at Boystown National Research Hospital.
A DP gram we use to plot responses from the cochlea of a gargoyle.
A version of a DP gram with normative values from the 5th percentile to the 95th percentile used to indicate if hearing is normal, abnormal or borderline.
What is the optimal dB SPL for the stimulus when recording a TEOAE?
74-83 dB SPL
Passive cochlear processing (when a sound is loud enough) can directly stimulate which of the following?
The semicircular canals
The outer hair cells as biological amplifiers
The inner hair cells stimulated through basilar membrane movement
The forward propagation of soft sounds
The inner hair cells stimulated through basilar membrane movement
OAEs can help you differentiate between a cochlear hearing loss and a retrocochlear hearing loss.
t
The OAE loses energy on the way from the cochlea to the ear canal where it is measured. Which of the following supports this?
Cerumen in the ear canal causes the OAE to lose energy
As the OAE moves from the cochlea to the ear canal, this reverse transmission is just as effective as forward transmission
As the OAE moves from the cochlea to the ear canal, this reverse transmission is much less effective than forward transmission
OAEs do not lose energy as they travel from cochlea to ear canal
As the OAE moves from the cochlea to the ear canal, this reverse transmission is much less effective than forward transmission
A pediatrician has referred his 2 year old female patient to you for testing. You choose to use TEOAEs. The parents report concerns that their child’s speech/language skills are delayed. The child uses about 5 single words expressively and “seems to understand” what they are saying. Results show passing responses in the 1000-4000Hz regions of both ears (6dB or greater above the noise floor, 99% stability, 90% reproducibility, stimulus at 83dB SPL).
What will you report to parents and the referring pediatrician?
What other, if any, additional tests will you recommend?
Is OAE alone a test of hearing?
i would first let them know that the first test i ran she passed, but i would also break down the test for them and explain first, that OAE are not a diagnostic test nor does it show frequency specific information and that this test only tested 1-4K but i would explain to them how she passes in those frequencies but how i would need to do more testing to get more information especially in the higher frequencies since those are important for speech. I would also express when the most important time for speech and language development for a baby is birth to 3 (if they were reluctant for additional testing since she passed TEOAEs) and refer to a speech and language pathologist to be evaluated for a speech and language delay.
2) i would want to run Tymps, reflexs, and a full audiometric evaluation- I understand she is young so i would start with SRT and WRS first and go from there until she was no longer/tired and was done with the test. Also i probaly would done an DPOAE instead of TEOAE so i could get frequency specific information.
3) No, OAE alone is not a test of hearing.
A 49-year-old patient comes to see you from the Department of Labor. He had been seeking compensation after saying he had been electrocuted and had noise exposure, which was why he lost his hearing. His audiogram shows 50 to 60 dB thresholds, worse for the right ear. Reflexes were present and normal for both ears. There was a significant difference between the pure-tone average and the speech reception threshold (SRT) with his SRTs being much better. You perform transient OAEs after the audiogram, which are normal for both ears for all frequencies tested.
Is there anything you are suspecting at this point?
What do you do next?
What role did OAEs play in this case?
Yes, Abnormal audiogram and normal OAE i would consider Functional HL, Non organic, and phyogenic HL, Central Nervous system dysfunction, 8th nerve auditory dysfunction, and inner hair cell damage (cochlear dead regions). However looking further into his result, i would take note of abnormal Air and not supportng SRT with a much better result that what would be an agreeance with his AC threshold. from there i would take a step back and look at his whole case hsitory and the reason he came in would suppect. I would suspect a non- oroganic HL.
i would also run Tymps to check middle ear status, I would first reinstruct the patient and give them a chance to try and be honest, i would let them know my data isn’t adding up and ask them if they understand the directions and if that doesn’t work i would follow up with the stenger test to see if i got a positive or negative. depending on the stenger test i would stick with my original suspicion move on to a differential diagnosis. (another option could be functional HL, this the other thing i would consider if the stenger test did not support my non-organic suspician)
the role the OAE’s played in this is it gave me a picture of how the outer hair cells and cochlea were functioning to see if there was any pathologies or any concerns with hearing sensitivity i should keep in mind when beginning the audio. Even though OAE’s are not a test of hearing on its own, during this i would use the cross check principle to validate my data. which i was able to do for this case.
