Exam 2 Flashcards
What type of testing does immittance testing encompass?
tymps, Tympanometry, Ear canal volume measurement
Acoustic reflex testing (Acoustic reflex threshold
Acoustic reflex decay) Tests of Eustachian tube function
What structures are assessed using immittance measures?
tymp middle ear
reflexes - effect on middle ear, auditory nerve, cochlea, b.s., facial nerve
What are the components of an immittance meter?
probe signal (tone)
air pressure
microphone
How is immittance testing conducted?
based on changing the pressure in the ear canal and measuring sound levels in the ear canal
Define the term acoustic immittance
Flow of sound energy
acoustic immitance evaluates
Tympanic membrane
Middle ear space, including ossicles
Middle ear reflex
Involves middle ear
Cochlea
Auditory nerve
Auditory brainstem pathways
Facial nerve
Describe the instrumentation for immittance measures. What are the three components of the probe for tympanometry?
probe itself has 3 components
tone that is played when tymp is ran
microphone picks up sound in me space while running it
air pressure - changes air pressure
how does immitance testing work
sound goes into the ear, changes the pressure and measure the sound in the ear as the pressure changes by the microphone= tymp
what is on the y axis for immitance
admittancew
what is on the x axis for immitance
time? or Pressure?
How is a tympanogram derived? What is the premise underlying tympanometry? (Hint: it has to do with the admittance of the middle ear and pressure.)
Changing the air pressure in the ear canal in either direction cause TM and ossicular chain to stiffen
Increase impedance
Decrease admittance
Measure sound transmission at each pressure point and compare to norms
Peak admittance occurs when pressure in the ear canal is roughly equivalent to pressure in the middle ear
adult norms for static admittance, tympanometric peak pressure, ear canal volume, and tympanogram width
Peak Compensated Static Admittance (Ytm) 0.3 – 1.7 mL
Tympanogram Width (TW) 50 – 115 daPa
Equivalent Ear Canal Volume 0.9 – 2.0 ml
Tympanometric Peak pressure: -100 to +50 daPa
what does ear canal volume measure
Ear canal volume provides useful information about the status of the TM
Intact TM
Patent PE tubes
Ear canal volume provides information about the ear canal
Estimate blockage
Surgical ear
what is static admittance on a tymp
tymp peak height
what does static admittance measure
Static admittance - Ytm
Frequently referred to as compliance or peak compliance
Measures stiffness or “floppiness” of the ossicular chain/middle ear system
what is tymp peak pressure
point where middle ear system is operating most efficiently
what does tymp peak pressure measure
Peak approximates but does not measure middle ear pressure
what is a type a
normal
peak in the box
what is As
shallow peak
associated with otosclerosis and can with otitis media
peak below the box
what is Ad
high peak
above the box
found in ossicular interruptions or scarred/flaccid eardrums
what is type b
flat across all pressure ranges
middle ear fluid and cholesteatoma or eardrum perfs and impacted cerumen
what is type c
Negative pressure peaks beyond -100 daPa
Indicating negative ear pressure
Peak is to the left of the box
Associated with eustachian tube disorders
Also found in cases of middle ear fluid
Which muscle is involved in the middle ear muscle reflex in humans?
stapedius
What are the two clinical uses of the MEMR/ASR?
cross check
determine site of lesion
What measurement (from the tympanogram) changes in the ASR?
admittance, performed at the peak pressure
What is the minimum amount of change in this measurement that would be considered a reflex?
.02
What are the five criteria for a reflex?
Lowest level that elicits “criterion change”
2. Time locked to stimulus onset
3. Replicable
4. Growth- stronger response present 5dB above/ Reflex is stronger the further you go above threshold.
5. A decrease of admittance.
what measure from the tympanogram changes when an acoustic reflex is present
admittance
What is the minimum amount of change required to consider a reflex is present?
.02
What is considered a normal ASR?
70-90 dB SL?
An acoustic reflex would be expected with hearing loss up to what level (cochlear)?
60 dB HL?
what is acoustic immittance
flow of sound energy
what is acoustic impedance
opposition to energy flow
what is acoustic admittance
ease of energy flow
Describe the instrumentation for immittance measures. What are the three components of the probe for tympanometry?
probe itself has 3 components
tone that is played when tymp is ran
microphone picks up sound in me space while running it
air pressure - changes air pressure
what is on the axis of tymps
x is pressure and y is admittance
How is a tympanogram derived? What is the premise underlying tympanometry?
How is it measured? What is the machine doing?
Changing the pressure and plotting admittance as the pressure changes
The admittance is greatest when the ear canal pressure roughly matches the middle ear pressure
what are the norms for static admittance
.3-1.7 mL