Exam 1 Study Guide Flashcards
What is the presentation levels for TEOAEs?
74-83 dB SPL
What is the presentation levels for DPOAEs?
65 (L1) and 55 (L2) dB SPL
Are there national standards for a passing OAE?
No
What is generally accepted for passing rates for OAEs?
6 dB SNR (TEOAE and DPOAE)
Must also look at reproducibility and DP amp
What is the stimulus stability for TEOAEs?
Consistency of a stimulus intensity throughout the period of data collection
Percentage
Higher stability preferred
What is TEOAE reproducibility?
Correlation
A and B waveforms should approx 100%
Two waveforms will overlap almost totally
What are the accepted guidelines for a passing DPOAE?
SNR of at least 6 dB and a DP of -10 or better
What is the stimulus frequency for DPOAEs?
Activated by 2 tones (primary tones)
f2 (higher frequency) and f1 (lower frequency)
What is the stimulus intensity for DPOAEs?
L1=65 dB
L2=55 dB
Needed to elicit the best DPOAEs in humans
What are the largest DP evoked tones in the human ear defined by?
2f1-f2
Are DPOAE equipment algorithms designed to detect energy at DP frequency ad distinguish it from noise in the ear canal at the same frequency?
Yes
What is plotted on a gorgagram?
DP amp as a function of stimulus frequency (f2)
Why is energy lost with backward transmission of the OAE?
Impedance mismatch
Less efficient due to smaller surface of oval window
Spiked heel effect
What is passive processing of the cochlea?
Activated with stimulus of 70 dB SPL or higher
Likely vibration of the basilar membrane
Not measuring the actual motility (lengthening and shortening) of the OHCs
With lower intensity levels, what are we triggering?
Only the OHCs
Stimulus invokes movement of the BM, causing OHCs to move or be deflected
Causes stereocilia of OHCs to bend
What happens after stereocilia bend in the OHCs?
Ions rush in and out changing membrane potentials within the hair cells
Voltage changes across plasma membrane cause electromotility
OHCs are absent when electromotility is blocked
What are standing waves?
Cancellations and reinforcements of some sound waves or interaction between stimulus sound wave moving toward TM and OAE sound wave moving outward from TM
Are standing waves a problem with both TEOAEs and DPOAEs?
No, just DPOAEs
Because they are usually at frequencies at and above 6k
What is one way to resolve standing waves?
Place mic at TM, but its not clinically feasible
Can you do OAEs on someone with negative ME pressure?
It is not prohibited
Recorded except in extreme negative pressure when ABR exceeds 15
Low frequencies affected first
Can you do OAEs on someone with PE tubes?
You can, but you might not get anything
Can you do OAEs on someone with a perf?
You can, but you might not get anything
Can you do OAEs on someone with ME effusion?
It depends on the viscosity of the fluid
If it is yellowish, they probably won’t have any
A lot of people won’t even try
Can you do OAEs on someone with ossicular fixation?
No
Can negative middle ear pressure affect OAE measurements?
Yes
Can reduce amplitude or entire response
What is the cross check principle?
The use of subjective and objective tests
You might consider a functional hearing loss if the cross check principle doesn’t add up
What is an example of the cross check principle?
Do some people think that OAEs are related to tinnitus?
Yes, some people think that OAEs are effected in the frequency region of the tinnitus
Where is tinnitus theorized to originate?
Both the cochlea and the central auditory system
Do studies show consistent TEOAE results between tinnitus patients with hearing loss and those without?
No
Cannot conclude that OAEs give objective evidence of tinnitus
More research is needed
Are OAEs often present in tinnitus patients?
Yes, but entirely normal findings are rare
Is tinnitus often related to cochlear dysfunction associated with either aging and/or noise exposure?
Yes
Are OAEs useful in predicting cochlear function?
Yes
Can OAEs be useful for site of lesion and for separating out sensory from neural in SNHL?
Yes
Can OAEs also be abnormal in conductive/mixed losses due to the inability to record?
Yes
How are OAEs used in NBHS?
Used in isolation with the goal of distinguishing infants with normal hearing from those who need further intervention
How are OAEs used in adult cases?
Best applied as part of a comprehensive test battery approach
Cross-check
Are OAEs a test of hearing?
No
Peripheral hearing sensitivity is inferred from them
What do OAEs tell us?
Function of the cochlea OHCs
What do OAEs not tell us?
Neural or cortical information
Are OAEs sensitive to damage before it shows up on an audiogram?
Yes
What are some of the clinical uses of OAEs in adults?
Suspected functional hearing loss
Tinnitus
Ototoxicity
Noise exposure
Cochlear vs retro
What are some conditions that might result in an abnormal OAE with normal pure tones?
Tinnitus
Noise exposure
Ototoxicity
Vestibular pathology
What are some conditions that might result in normal OAEs with abnormal pure tones?
Functional hearing loss
Central auditory nervous system dysfunction
8th nerve auditory dysfunction
Those with inner hair cell damage (exclusively)
What type of hearing loss are OAEs not expected?
35-45 dB HL to profound loss
Can OAE findings be correlated with pure-tone audiometric threshold levels?
No because there is inter-subject variability
Can OAEs be used to accurately estimate degree of hearing loss?
No
What are the three categories of OAE outcomes?
Amp is normal (relative to an appropriate normative region)
Amp is abnormal (present but below normal)
No evidence of reliable OAE activity above an acceptably low noise floor (absent)
What do DP-grams and gorgagrams plot?
Measure amp at a frequency
What is a gorgagram?
A type of DP-gram
What are the thresholds for TEOAEs?
SNR: greater than 6 dB
Repro of 70% or greater
What does it mean if SNR and repro meet the requirements for TEOAEs?
It means you have present OAEs at all the tested frequencies