Unit 4 Flashcards
What is Immittance Audiometry?
It is an objective measure of tympanic membrane (TM) & middle ear function.
What kind of information will immittance audiometry give us?
- The compliance or movement of the middle ear ad the tympanic membrane (tympanometry)
- The middle ear pressure (tympanometry)
- the volume of the ear canal (PVT)
- at what level the auditory reflex to loud sounds can be achieved (acoustic reflex threshold)
What is Immittance Bridge/Meter?
- Used during immittance testing
- A probe is fit into the ear canal
Immittance Bridge: Does an airtight seal need to be obtained to complete the measurement?
True!
The Immittance Bridge instrument ie probe has three ports… What do they do?
- One is to emit a tone (speaker)
- One is to measure the tone reflected back (microphone)
- One is to change air pressure (pump changes pressure, manometer indicates what the pressure is)
What are the subtests of Immittance Audiometry?
- Tympanometry
- Physical Volume Test (PVT)
- Acoustic Reflex Threshold
What is tympanometry?
A measurement of middle ear pressure and/or the compliance of ear drum and middle ear system.
The movement of the tympanic membrane is determined by how much of the emitted tone is reflected back.
When will the compliance or the movement be limited for tympanometry?
The compliance or movement will be limited if there is fluid in the middle ear, otosclerosis, tympanosclerosis, etc
First stage of tympanometry
- A 226 Hz tone is sent into the ear canal and reflected off the membrane. This reflected tone is sensed by the microphone in the probe.
2nd stage of tympanometry
The pressure port of the probe changes the pressure in the ear canal from positive to negative (_ to - daPa)
What is pressure measured in?
Pressure is measured in daPa or dekapascals
Third stage of tympanometry - What is this called?
As the pressure changes in the ear canal the least amount of tone will be reflected back when the ear drum is most compliant or when the pressures on both sides of the ear drum are equal.
Peak Pressure Point
This is how the tympanogram can determine the pressure of the middle ear.
What do you do in tympanometry if there is no movement of the ear drum?
This will happen if the middle ear is full of fluid.
A large amount of the tone will continue to be reflected back to the microphone even when the pressure is changed in the ear canal.
For Tympanometry, what does the x-axis indicate and the y-axis?
x-axis indicates the amount of pressure in the ear canal and y-axis shows the compliance or mobility
What is the Type A tympanogram?
A normal TM (tympanic membrane) movement, normal compliance and peak pressure.
What is the Type B tympanogram?
Flat, limited compliance or movemet. Possible otitis media.
What is the Type C tympanogram?
Peak is shifted to the left indicating negative peak and middle ear pressure but normal compliance. Possible eustachian tube dysfunction causing negative middle ear pressure to buildup.
What is the Type A(S)?
Too shallow, reduced compliance but normal pressure. Possible otosclerosis.
What is the Type A (D) tympanogram?
High peak, hyper-flaccid, high compliance, normal pressure. Possible disarticulation of ossicles.
Immitance audiometry is an important part of the ______ ______ ________________.
Immitance audiometry is an important part of the audiometric test battery.
What can the measurement of immitance can assist diagnosing what?
The measurement of immittance audiometry or middle ear function can assist the audiologist in diagnosing the type of hearing loss.
What is Physical Volume Test (PVT)?
Measures the volume in the ear canal between the probe and the tympanic membrane. Measures how big the ear canal is.
When is PVT automatically measured?
It is automatically measured when tympanometry is performed.
What is the normal volume for PVT?
Children - 0.3 to 1.0 cc (or ml)
Adults - 1.0 to 2.0 cc (or ml)
