Exam 1 Study Guide Flashcards
what is the current and excepted definition of OAEs
low level sounds emitted by the cochlea, either spontaneously as an echo or other sound evoked by an auditory stimulus, related to the fxn of the OHC of the cochlea
two types of noise
body & environmental
why is energy lost during backward transmission
impedance mismatch
backward transmission is less efficient; the oval window is a smaller surface area sending signal to a larger surface (TM) via the ossicular chain that results in a loss of intensity during the transmission
spiked heel effect
what is the spiked heel effect
Sound goes from a big area (TM) to a tiny one at the oval window which creates more pressure or the spiked heel effect (pretty sure it relates to the area size difference we learned in anatomy)
Stepping on your foot with more surface area doesn’t hurt as much as stepping on it with less surface area like a stiletto heal
So the stiletto has more pressure on it because it’s a smaller area than if you were to step on it with the ball of your foo
describe inward propagation of OAEs
stimulus is presented in teh EAM with a probe & delivered to the TM then the ME
role of the ME in OAEa
both stimuli sent in and OAEs coming back out travel to and from the cochlea via this space therefore the health of ME influences OAE recordings TWICE
in: has mechanical advantages like the area ratio bw tm and oval window, lever action of ossicles, and the geometry and placement of the eardrum
out: not efficient coming out, systems that act as an impedance matcher hinders the reversal transmission
describe the outward propagation
it is an impedance mismatch; distortion picked up is so small because of the force it takes to push back out because it doesn’t have the ME impedance matching to assist it
backward transmission is less efficient becaues the oval window is a smaller surface area sending the signal to a larger surface (TM) through the ossicles, resulting in a loss of intensity during transmission
spiked heel effect
Impedance mismatch on outward propagation can decrease up to
15 dB.
what is a travelling wave
Displacement wave traveling along the BM from base to apex
cancellations and reinforcements of some sound waves or interaction bw stimulus sound wave moving toward the TM and OAE sound wave moving outward from the TM
Describe the importance of basilar membrane to OAEs
OAEs are generated by the movement of the BM
BM is displaced to its max displacement with different stimuli frequencies
describe the role of OHC in OAEs
lower intensity levels activate ohcs (65/55 DPs & 79-83 for TEs)
bm moves from stim causing OHCs to be deflected and stereocilia bending in one direction
ions rush in and out changing the membrane potentials in the hair cells
voltage change across plasma membrane causes electromotility (lengtheneing & shortening of OHCs)
how do OHCs become absent
when electromotility is blocked
what is electromotility
the shortening and elongating of OHCs
generators of OAEs
OHCs
what is the fxn of the OHCs
improve sensitivity to sound (100 fold increase, 40dB)
make thresholds lower
AMPLIFY
damage results in mild to mod-severe SHNL
3 rows in a v pattern
OHCs
what happens to IHC after activation from OHCs
traveling wave in cochlea that moves the BM from stapes pushing into oval window finding the best movement, (vibrates best at apex for this 500 Hz example), IHC gets its stereocilia sheared shortest to tallest (tip links fanning open) potassium rushes in (high in endolymph), depolarizes causing the triggering of calcium to rush in from opening of calcium ion channel ,calcium rushing in causes which causes the neurotransmitter (ligand/chemical) vesicle to rush to the edge of the cell and dumps out onto the synaptic cleft (glutamate). NT binds to receptor sites on CN VIII causing ligand gated ion channels to open and depolarize the cell (excitatory post-synaptic potential).
describe what happens after NT is dumped onto the CN viii
stimulated enough starts ap, ap - voltage gated channel opens to allow for sodium to rush in and depolarize spot on cn 8, spot resets itself after absolute and refractory period and is maintained by sodium potassium pump, action potentials move forward to next node etc., process repeats. propagates down cn 8, cn 8 enters cns at cerebellopontine angle synapsing on cn (AVCN, PVCN, DCN)
the actual sensory receptors of hearing
IHC
damage causes severe to profound SNHL
ihc
1 row in linear pattern
ihc
this allows the cell to signal the VIIIth Nerve
Hair cells in the cochlea turn mechanical energy of sound waves into a change in membrane potential
what is the role of the efferent system
Don’t need them to get outer hair cell motility/ cochlear amplifier
May modify motility or cochlear amplifier.
Reduction in masking
Selective attention
Protection from intense sound
Adjust input to two ears to maintain balance
Not clear why efferent innervation of OHCs affects cochlear responses
true
active processing
OHCs
passive processing
IHC
when is passive processing activated
activated with stimulus of 70dBSPL (75 dB) or higher
Likely vibration of the basilar membrane
Not measuring the actual motility (lengthening and shortening) of OHCs
Negative middle ear pressure can affect OAE measurements by
reducing amplitudes or entire responses
how does ME pressure affect TEOAEs
as little as -35 to -65 daPa can affect
how does ME pressure affecct DPOAEs
DPOAEs >-100 daPa or less can affect
worse in ____ frequencies with less effect, if any at _____ frequencies
low frequencies (<1000-2000 Hz)
high frequencies
what is not often done clinically with ME pressure
Consider adding pressurization to OAE recordings to overcome suboptimal middle ear transfer mechanism
do we still test OAEs with neg me pressure
yes may result in reduction of OAE amplitude or be absent
should you do OAEs with perfs
yes they can be recorded if ME is otherwise normal
Will the stimulus be strong enough without the vibration of the ™ to get to the inner ear to record an oae?
sometimes
varies by individuals
Which frequencies are most affected by a perf or tube?
LF
can you still do OAEs with Tympanostomy / Ventilation tubes
OAEs may be recorded if there is a patent tube and no active middle ear pathology but the likelihood of OAE presence <50%.
If OAEs are reliably present and, in particular, within the normal region, it can be concluded also that:
the tubes are patent,
there can be little or nor middle ear dysfunction, and
Significant cochlear dysfunction is effectively ruled out.
otosclerosis and OAEs
OAEs typically not detected at any frequency for any degree of hearing loss though much like immittance presentation may vary slightly based upon stage of disease
Why wouldn’t you have OAEs with otosclerosis
with the stiffness, it cannot get through the ME efficiently to stimulate the cochlea and get an OAE
neonatal fluid and OAEs
persists in ME space around a day
48hrs after birth, ME usually aerated and ™ mobile
what is mesenchyme? how does it affect OAEs
form of connective tissue located between epithelium and bone
fetal ME contains this and it is usually reabsorbed at the end of pregnancy or soon after birth but can persist up to a year after birth
if you see fluid line in ME on otoscopy
can run OAE and see
bulging tm that is yellow
do not perform OAE
2 clinical advantages of oaes
site-specificity of OAEs to auditory dysfunction
high degree of sensitivity specifically to cochlear impairment
what is high degree of sensitivity specifically to cochlear impairment
Considerable evidence shows that noise or music induced cochlear damage is detectable with OAEs before it becomes apparent in the audiogram
what is site-specificity of OAEs to auditory dysfunction
is loss purely sensory (cochlear), purely neural (retro) or does it involve sensory and neural structures?
can be answered with OAEs and ABRs
why does she hate robust
you cannot quantify it
what are the differences between diagnostic and screening OAEs
you use fewer frequencies with the screening, you get an automatic result, and you went to screen from highs to Lows
What are 3 ways OAEs are affected by the efferent system
protects cochlea from trauma
improved ability to detect stimuli in background noise
attention
how does age affect OAE
decrease in OAE amp
abnormal findings in adults should consider aging as a factor
why does age change OAEs
intensity level and ear canal anatomy
ear canal resonances changes
ME status changes
maturation of efferent function
what are non pathological subject factors
age, gender, ear differences, noise
noisy rooms, right ears are better, women are better, declines over age
how does gender affect OAEs
males are less sensitive, lower, and slower responses to signals than females
DPOAE latencies are longer in males
TEOAE amps and reproducibility values are higher in females than males
what are 4 factors that may explain the gender differences
differences in cochlear length
differences in hearing sensitivity
tinnitus
more SOAEs in females
how do ear differences affect OAEs
right ear hears better especially for higher frequencies
how does noise affect OAEs
the success of an OAE measurement and the accuracy of OAE interpretation is highly dependent on noise
describe TEOAEs
has a probe with 2 ports - one delivers click & other records emission
look for >75% reproducibility
stim between 78 to 83, not exceeding 83-85
min 40-50 sweeps
SNR of >/= 6dB spl
non linear, 800-5000 Hz
what does a pass TEOAE mean
normal or near normal peripheral hearing for the specified frequency region which pass occurred
hearing is </= 30-35dB
if there are present TEOAEs what does the information look like
SNR >/= 6dB
75% or > reproducibility
what is the stimulus for teoae
80 microsecond , brief click
what is the fast fourier transform analysis
.8-5 kHz
takes the broadband signal that comes back out and puts it into frequency specifics to analyze
what is the presentation level of TEOAE
80-85dB or 74-83 dB
what is reproducibility in TEOAE
correlattion
a and b waveforms should approximate 100%
two waves should overlap
what relates to lower correlation
too much noise or probe fit is incorrect
what does the response look like in TEOAE
alternating responses are stored in alternating computer memory banks, a and b
want them to overlap
describe DPOAEs
3 ports in the probe - f1 f1 and recording
2 pure tone stimuli
measures 2f1-f2 (abs amp, dp)
500-8000 Hz
L1 - 55, L2 - 65, L1-L2 = 10 dNB
F2/F1 ratio = 1.22
what criteria is a pass DPOAE
absolute emission/absolute amp/DP - >/= neg 10
SNR >/= 6dB
can be plotted on dp gram or gorgagram
if criteria is met for DPOAE and polotted on gorgagram at normal
hearing is better or equal to approximately 15-20 dB HL
if criteria is met and did not use a gorgagram
hearing is expected to be better than or equal to approximately 25-35 dB HL
what does 2f1 - f2 represent
DP value
if f1 is 2000, what is f2, dp, and where is it plotted at?
2000 x 1.22 = 2440 (f2)
2(2000) - 2440 = 1560
DP = 1560
Plotted at 2440 (f2)
when plotted on the graph, where is it plotted? why?
F2 because it is the main contributor to basilar membrane movement that creates the distortion product from research
what is the stimulus of DPOAE
2 pure tones
F2 is the higher frequency, F1 is the lower frequency
what is the stim intensity of DPOAE
L1 = 65
L2 = 55
what is the largest dp evoked by tones in humans
defiend by 2f1-f2
what is the difference between screening and diagnostic OAEs
screenings are fast, portable, not as expensive, get an automatic result, screen from highs to lows, fewer frequencies used
diagnostic provide valuable info in assessment and diagnosis
diagnostic OAEs provide valuable info in assessment and diagnosis of
PT that cannot complete behavioral testing
non organic HL
noise induced HL
ANSD
cochlear vs retro
ototoxic medictation
are OAEs a direct measure of hearing
no
only tells us the fxn of cochlea’s oHC from which we determine cochlear function
ALMOST direct measure of OHC integrity but not because of ME fxn as a factor in OAEs
OAE amp within normal range
0-15dB hl
OAE amp below normal limits but >6dB above the noise floor
15-30dB HL
OAEs probably not observed
35-50dB HL
OAEs are not observed
> 50 dB HL
OAE outcomes fall in 1 of 3 categories. what are they
amp is normal (relative to an appropriate normative region)
amp is abnormal (OAE is present but below normal limits)
no evidence of reliable OAE activity above an acceptable low noise floor (abs)
Objective in most applications is to
describe cochlear function
what are 2 clinical advantages to OAEs
site specificity: determine retro vs cochlear or both
cochlear impairment sensitivity: noise/music induced cochlear damage is apparent on OAEs before in an audio
abnormal thresholds but normal OAEs could have 3 possibilities
pseudohypacousis
retro pathology
pt may superimpose fxnal HL on pre existing sensory impairment
what are the clinical applications of OAEs in adults
assessment in suspected fxnal hl
tinnitus
noise/music induced
differentiate cochlear vs retro
monitoring ototoxicity
meneire’s disease
_____% of retro path had normal OAEs
associated with higher chance of hearing preservation post op
20-25
how does tinnitus affect OAEs
originates in cochlea and cas
cannot conclude that absent OAEs give objective evidence of tinnitus
see present OAEs, but not entirely normal
measurable SOAEs are not linked to tinnitus but some PTs tinnitus frequencies coincides with
frequencies of the SOAEs
how can OAEs help with noise/music induced
can provide an early and reliable warning sign of cochlear dysfunction before it shows on the audio
can provide objective confirmation of even mild cochlear dysfunction in PTs with normal audios
what are the two patterns of OAEs seen in Meniere’s
majority with snesory hL secondary to meniere’s - OAEs are abnormal with HL >/= 25-35 dB - do not expect OAE activity
some have TEOAEs or DPOAEs w/ normal or even greater than expected amplitude values with thresholds exceeding 30 dB HL or up to 60 dB HL
what is the crosscheck principle and examples for OAEs
a single test may not be accepted or used in a diagnosis of hearing loss until it is confirmed by one or more other measures
behavioral audiometry, immittance, abr
why does cunningham hate robust
cannot quantify the term
what is a gorgagram
type of dp gram
goes into hearing levels - normal, borderline, abnormal
plots dp amp as a fxn of f2
what is a dp gram
plots SNR at F2
nothing about HL
graphs dp as a fxn of stimulus frequency, usually f2
can we estimate hearing when we only use a dp gram
NO
can only state that HL if passing the criteria is expected to be better than or equal to approx. 25-35 dB HL
what is cunningham’s occupation
pediatric audiologist
currently clinical and educational audiologist
where does cunningham live
indiana
has been friends with buck for
over 30 yrs
how long has cunningham taught OAEs
20 yrs
what is her favorite team
colts
peyton manning
what animals does cunningham have
cats and dogs
what is significant about Cunningham’s dog
barks at 6:25 when her husband comes home
her and the dog are a certified therapy team and go to libraries and the Peyton Manning Hospital
does she have children
yes
1 girl and 3 boys
where did she get her phd in audiology
cincinnati 2000
where is cunningham a pediatric audiologist at
Deaf and Hard of Hearing Education/Indiana State Department of Health
where was her ba from
speech and hearing sciences 1991 indiana university
where was her masters of audiology from
Purdue universityn1993
