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
