midterm 2 Flashcards
acoustic immittance
flow of sound energy
-we can do a variety of tests with the immittance machine
acoustic impedance
opposition to energy flow
-how much sound does not get through
acoustic admittance
ease of energy flow
-how much sound gets through
what type of tests are included for an immittance test
tympanometry, ear canal volume measurement, acoustic reflex testing and tests of eustachian tube function
what do immittance tests involve
changing the pressure in the ear canal and measuring sound levels in the ear canal
what do immittance tests evaluate
tympanic membrane, middle ear space and middle ear reflex
instrumentation for immittance measures
immittance meter
3 components of the immittance
microphone, probe tone, pressure system
clinical applications of immittance testing
evaluate middle ear function/middle ear disorders and differentiating cochlear from retrocohlear disorders
low admittance is _________ and high admittance is _________
stiffness ; floppiness
how is a tympanogram derived
probe is placed in the canal, pressure is changed in the canal from negative to positive, sound levels within the canal are monitored during the change in pressure, admittance is calculated at each pressure point, peak admittance occurs when pressure in canal is equivalent to pressure in the middle ear
changing the air pressure in the canal causes the membrane and ossicular chain to ________
stiffen
-increase impedance and decrease admittance
-measure sound transmission at each pressure point and compare to the norms
static admittance (Ytm)
admittance when the pressure on either side of the TM are relatively equal, the best point (in mL)
norms : 0.3-1.7 mL
anatomical structures : stiffness or floppiness of the ossicular chain/middle ear system
tympanometric peak pressure (TPP)
point where the middle ear system is operating most efficiently (in daPa)
norms : -100 to +50 daPa
anatomical structures : eustachian tube function and could lead to early identification of OME
ear canal volume (Vea)
if TM is intact or not if there is something taking up space within the canal (cc or mL)
norms : 0.9 to 2.0 mL
anatomical structures : information about the ear canal (blockage, surgical ear or occluded) and about the TM (intact or perforation or PE tube)
tympanogram width (TW)
referring to the width at the halfway point
norms : 50 to 115 daPa
tympanogram shapes
type A - within norms
type B - flat (fluid or perforation)
type C - very negative peak (eustachian tube function)
type Ad - tall peak (system is floppier)
type As - shallow peak (shallow or stiff system)
how are shapes varied for tympanogram based on their values gained
type A - within norms
type B - width is really wide or no width
type C - peak pressure is lower than norms
type Ad - static admittance greater than norms
type As - peak is below norms
why are numbers preferred to describing the shape
numbers are more precise and give a more accurate representation of the peak
what measures from the tympanogram change when an acoustic reflex is present
admittance
what is the minimum amount of change required to be considered a reflex
0.02 mmho or mL
acoustic reflex
impedance increases when a loud sound is presented to either ear
-middle ear muscle reflex stiffens the middle ear system
-bilateral response
the STIM ear is _______, the PROBE ear is ________
playing noise ; measuring
right contralateral reflex
STIM : right
PROBE : left
left ipsilateral reflex
STIM : left
PROBE : left
left contralateral reflex
STIM : left
PROBE : right
right ipsilateral reflex
STIM : right
PROBE : right
5 criteria for a reflex to be valid
-must reach 0.02 of change
-time locked to stimulus onset (occurs right after it started)
-replicable
-growth (stronger response at 5 dB above)
-decrease in admittance (not increased)
what is a normal ART
between 70-90 dB SL is typical
an acoustic reflex is expected with HL up to _______ dB
60
reflex patterns with normal hearing
-hearing thresholds normal
-reflexes present at 70-90 dB SL
reflex patterns with conductive HL
-hearing thresholds show CHL
-reflexes ABS when the affected ear is the PROBE ear
-affects the descending pathway
reflex patterns with cochlear HL
-hearing thresholds show SNHL
-reflexes are less than 70 dB SL when affected ear is the STIM ear
-affects the ascending pathway
reflex patterns with retrocohlear HL
-hearing thresholds show SNHL
-reflexes are increased above 90 dB SL or ABS when the affected ear is the STIM ear
-affects the ascending pathway
reflex pattens with brainstem pathology
-both contra reflexes will be ABS or NR
-occurs at the crossing over point
reflex patterns with facial nerve pathology
-hearing thresholds normal
-reflexes are ABS or NR when the affected ear is the PROBE ear
-affects the descending pathway
-we expect reflexes based on no HL but we do not get them
reflex patterns with SSCD
-hearing thresholds are CHL
-reflexes will be present
-CHL but no effect on reflexes
reflex patterns with ANSD
-hearing thresholds are SNHL
-reflexes are ABS or NR everywhere (if bilateral) but expect STIM effect if unilateral
what pathway is affected with the PROBE ear?
descending pathways
what pathway is affected with the STIM ear?
ascending pathways
how to differentiate different HL types based on air conduction and reflex thresholds
look at overall patterns
-use the reflexes to detect patterns and use the audiogram to help rule out certain aspects
sensitivity
correctly identifying those with a disease
-tells us how good our test is at identifying those with the disease
-to find : TP / (TP + FN)
specificity
correctly identifying those without the disease
-tells us how good we are at identifying those without the disease
-to find : TN / (FP + TN)
how to fill out a sensitivity and specificity chart
have disease (+ and -) on top with test (+ and -) on the side and use the following parameters to fill in :
TP - those that are positive for the disease and tested positive
FP - those that do not have the disease but tested positive
TN - those that do not have the disease and tested negative
FN - those that have the disease but tested negative
is standard low frequency tympanometry a good differentiating tool between otosclerosis and a normal middle ear?
it is not, we can still get good low frequency tympanometry scores in individuals with otosclerosis
AAA protocol for OME screening
-calibrate equipment daily
-screen with OAE or tones before doing tymps
-refer if TW and/or static admittance suggest flat tymp
-NPP greater than -200 (cannot refer on this alone)
common use of high frequency audiometry
monitoring for ototoxicity
what transducer must be used for high frequency audiometry
circumaural headphones
an abnormal static admittance volume reading would suggest a disorder associated with the __________
tympanic membrane and/or ossicular chain
an abnormal peak pressure reading suggests a disorder associated with the ________________
eustachian tube (not functioning)
-abnormally negative reading
an abnormally low ear canal volume reading suggests a disorder associated with the _____________
ear canal (blockage)
-low means something taking up space
an abnormally high ear canal volume reading suggests a disorder associated with the ____________
tympanic membrane (perforation)
