Test 3 Flashcards
Simple definition of mechanical impedance
how much force is needed to set a physical system in motion.
Simple definition of acoustic impedance
how much force is needed to transmit sound energy through the ear.
High Admittance
when theres too much flow because ossicles are broken
High Impedance
Too much fluid in Middle Ear which causes too much resistance
Acoustic Reflex Threshold:
Tests reflex of stapedius muscle
To test middle ear (tymp) what is a must?
The ear canal must be clear
When reading a tympanogram what are the 3 things we are looking for?
Compliance, pressure, and volume
Type A
Normal
Type As
- tymp. membrane and ear drum is very STIFF
- Compliance is abnormally LOW
- see w/ otosclerosis b/c ossicles aren’t moving enough
Type Ad
- compliance unusually HIGH
- ear drum is very flexible, maybe stapes has broken off
- looks like ossicular discontinuity
Type C
- Compliance: NORMAL
- Pressure: ABNORMAL
Type B
- completely flat
- 0 compliance and pressure
- ear drum did not move at all
- otitis media, FLUID in ME that doesn’t allow for ear drum to move: normal ECV
- or could have HOLE in ear drum: large ECV
If static admittance is high could have:
perpheration
If static admittance is too low:
problem w/ ME system
Tymp with abnormal ECV=
none. not looking at ECV. looking at pressure and compliance
Tymp with Abnormal pressure and Abnormal LOW Compliance
Type As and Type C
Tymp with Abnormal pressure and Abnormal HIGH Compliance
Type Ad and Type C
Normal compliance=
.3 to 1
Normal Pressure range=
-100daPa to +50daPa
Normal Volume Range=
0.9-2.0 cubic cm
Normal Static Admittance Range=
0.3-1.6cc
Normal OAE verifies what part of anatomy is functioning?
Outer Hair Cells
Will there be OAE results if there is a conductive HL?
No. Outer ear and Middle Ear must be normal to get OAE results.
What does ABR test?
CN VIII through LL
If there is an abnormal tymp, what type of HL?
Conductive
What is Acoustic Threshold?
what is the quietest to get it to reflex, to test AC
If normal tymp but abnormal OAE, what type of Audiogram would you expect?
Sensorineural
Abnormal tymp and abnormal OAE could be
Conductive or Mixed
Acoustic Reflex Arc Ipsilateral
outer ear, middle ear, inner ear, auditory nerve, cochlear nucleus, superior olivary complex, facial nerve, middle ear
Acoustic Reflex Arc Contralateral pathway
After SOC, to contra SOC to facial nerve to middle ear
Acoustic Reflex purpose:
What is the lowest dB level we can get stapedius muscle to contract
Normal Acoustic Reflex Result
normal sensation level (about 85dBSL)
Acoustic Reflex Outcomes
- Reflex may be absent at limit of reflex activating system (usually 110 to 125dB)
- reflex may be present, in case of hearing loss, but at low sensation level (less than 60dB above audiometric threshold
- reflex may be present but at high sensation level (greater than 100dB above the audiometric threshold
Absent Acoustic Reflex
damage to CNVIII, facial nerve
Acoustic Reflex Cochlear HL results:
high freq decay
Acoustic Reflex CNVIII
decay in 3-5sec at all freq
Acoustic Reflex Facial Nerve Damage
: rapid acoustic reflex decay
OAE Measurement
- Probe in EAC, contains mini speaker to present evoking stimulus and also tiny mic to pick up emission and convert it from sound to electrical signal
- Determines OHC function
- If present in known SNHL, then disorder is retrocochlear
Factors affecting OAE
- Poor probe tip placement
- Outer/middle ear dysfunction
- Noisy, uncooperative patient
- Ototoxicity, noise exposure, cochlear damage
OAE:
- ear makes sound back (ringing) twitch of muscle.
- outer hair cells produce sounds as they expand and contract.
Types of OAE’s
-Transient Evoked:Does not guarantee normal hearing
Cannot determine if hearing loss is cochlear or OHCs
-Distortion Product: most common test
Auditory Evoked Potentials:
- measure ear’s response to diff. sounds
- how long it takes for resonse to occur
- amp= how strong response is
- use ABR
Process of AEP:
- insert ephones.
- click stimulates cochlea
- EEG picks up response
- use to make sure everything is ok after surgery or if patient has downs syndrome
ECOG
- best tested near field on promonotory btwn oval and round window
- not easy to test
- often done during surgical process
- testing as soon as info. comes out of cochlea
ABR
- most common
- electrodes on mastoid or ear lobe and on vertex (center line)
- 7 waves, look for 1,3, and 5
For ABR waves 1,3, and 5 look for:
- time they occur
- time distance btwn certain waves 1&3, 3&5, then 1&5
- is info. taking longer than should?
- waves not occurring-something blocking
ABR Guidelines
- click stimulates entire cochlea or freq. specific tone burst w/ children to find threshold (freq. specific)
- must be in relaxed state , no clenching jaw, may sleep
- may do it at 1 vol-tumor
- change vol-threshold
Stacked ABR
- id very small vest. shwa.
- Measures whole nerve and whole cochlea by stacking amplitudes
MLR
- 15-60 msec
- Considered myogenic for long time, now considered neurogenic
- Patient must be awake but relaxed
- Assesses neurologic function of higher CANS
LLR
- no sleeping but need to be relaxed
- Use freq spec stimuli or short segments of speech
- Difficult to use with children
- Responses are called P1, P2, N1, N2 and P300
ASSR
-becoming more common to newborn screening
-Useful in threshold determination in children (shorter than tone burst ABR)
500, 1000, 2000, 4000Hz
-Patient may be asleep
Loudness Balancing
-Normal ears show logical progression of loudness as intensity increases
-Same is true of conductive hearing loss
ie 50dB tone above a threshold of 10dB (60dBHL), is equivalent as a 50dB tone above a threshold of 40dB (90dBHL) when conductive
SISI
- If can direct small changes in intensity
- present at 20dB above threshold
- Persons w. lesions of cochlea detect extremely small changes in intensity
- Cochlear loss detect each increase
- Retrocochlear, conductive and normal hearing will not detect all of them and may not detect any
Tone Decay
- able to hear a tone occurring
- cochlear tone will go away even if still presented
- 8th cranial=rapid decay
If HL is conductive, why would DPOAE results be abnormal
-outer and middle ear must be normal to test DPOAE b/c can’t even get to cochlea b/c O and ME are abnormal
Presbycusis
-age related HL
Otosclerosis
- will see decrease at 2000 Hz
- pregnancy, women, female relative, Type As
Sensorineural would be what type of Tymp
Type A
Pediatric MRL:
- Minimal Response Levels
- May be well above threshold
- May be anything from slight movement, change in vocalization or may be unobservalble, except for a change in electrophysiological system
Infant Hearing Screening
-mandatory
Newborn Hearing Screening Equipment
-ABR: Diagnostic equipment developed simply for this purpose
-OAE: May have higher failure rate bc of conductive loss
Cheaper, easier
-ASSR: More expensive, but may be part of ABR diagnostic equipment
BOA
- Behavioral Observation Audiometry
- Child sits on adults lap
- May use noisemakers, or other non-calibrated sounds
- Determine if child turns in response to sound
VRA
-Visual Reinforcement Audiometry
-Noise made
-Child looks toward sound
-Reinforcement given (animated toy, light, picture)
-May be done in soundfield or w. headphones
6 months until 3 years
Play Audiometry
-Can use stimuli through soundfield or earphones
-Can use screener/portable audiometer
Or can use 2 audiologists
-When sound is heard, toy is placed in bucket
Pediatric Sound Field Testing
- Narrowband, voice, warble tone
- Will not id if loss is unilateral or bilateral
- Look for child’s behavior in response to sound, Eye widening, Head turn, Eye turn, Stop crying, Startle
- May respond to sound turning off, instead of sound turning on
Pediatric Pure Tone
- May not give correct responses
- Two step directions
- Can ask where sound is coming from
- How many tones did they hear
Pediatric Speech Audiometry
Sometimes only responses you can obtain SRT, Spondee Touching body parts Point to people Ask questions Appropriate vocab
Pediatric Ling Sounds
/a/, /u/, /i/, /S/, /s/, /m/
Ling Six Sound Test
Use for SRT
Can use for CI verification
Pediatric Referrals
Concern about hearing loss due to: Language delay/disorder Other diagnosis Fail school/pediatrician screening Parental concern
Hearing Aids Gain
difference between input signal and output signal
Hearing Aids Frequency Response
Range of frequencies that can be amplified
NOAH
only way to program hearing aid
dmics
2 mics per hearing aid. one will pick up all sounds and other will pick up sound in direct direction (in front of you not noise behind you)
BTE
behind the ear, the best
ITE
in the ear (full)
Half Shell
half ITE
ITC
in the canal
CIC
Completely in canal
Mini BTE
receiver in ear/canal
CROS Aids
- normal in one, absolute 0 in other
- has mic that picks up sound and transferred to good ear
- good ear can hear on bad side
- no localization though
BICROS
-O in one ear, HL in better ear and signal is amplified
Bone Conduction Hearing Aid
- put screw behind mastoid and snap on box
- if conductive HL, no ear canal, treacher collins, otosclerosis
- functions as bone osscilator
- for unilateral HL, works 100% of time
Vibrotactile Hearing Aid
- use vibrations to send info.
- use elastic band on head and BAHA sits on back of head until old enough to have screw in head
Hearing Aids: Are 2 better than 1?
-yes, hear further and better, louder with both ears working
Binaural Deprivation
-if only 1 hearing aid, other ear gets lazy and decrease faster. PTAS and WRS
Data logging:
able to tell how often wear hearing aids, how often they turn it up
FM tech:
-use w. children in school. allows teacher to wear mic
Feedback (Hearing Aids)
when it whistles
Cochlear Implant
-electrically stimulates auditory nerve of patients w. severe to profound HL to provide environmental sound and speech info, especially suprasegmental elements
Implant Candidacy for Adults
-3-6 month trial period w. amp
-Show little benefit from hearing aids
-Score less than 40% on SRT
“Good attitude”- want to be part of hearing community
Overall good general health
Good emotional health and motivation to participate in intensive rehabilitation program
-if born deaf would really not be able to speak well
Admittance
Ease at which energy will flow through am vibrating system
