tymp types
Indicates normal middle ear function.
Type A
Define impedance.
The resistance to the flow of energy.
What are the 3 parts of the probe?
1) Loudspeaker
2) Air pump
3) Microphone
Normal pressure
Anything less than (not more negative than) -200 daPa
What are the two main hearing aid styles?
Behind-the-ear and custom.
Indicates an abnormal amount of middle ear stiffness.
Define admittance.
The ease at which energy flows through a system.
What does the loudspeaker do?
Creates the acoustic signal.
Normal ECV
Child: 0.4 to 1.0 ml
Adult: 0.6 to 1.5 ml
What are the main components of a hearing aid?
Microphone, amplifier, receiver, and battery.
Indicates a flaccid TM or possible disarticulation of the ossicular chain.
Type Ad
Define tympanometry.
The measurement of a change in admittance (in the TM) as air pressure is varied within the EAC.
NOT a test of hearing, but it is a test of middle ear function.
What does the microphone do?
Detects sound and compute immittance measures.
Normal Peak Admittance
Adults: 0.3 to 1.4 ml
Child: 0.2 to 0.9 ml
How do we select a hearing aid style?
The HA style a patient is fit with depends on their degree of hearing loss, their age, the physical structure of their ear, and the patient’s preference.
Referred to as a “flat” tympanogram.
Type B
What is a tympanogram?
A graph/plot of admittance (labeled as mmho) as a function of pressure (labeled as daPa).
What does the air pump do?
Changes the pressure within the EAC.
What does high, normal, and low ECV indicate in terms of type B tymp tracings?
High --> perforation / PE tube
Normal --> fluid
Low --> occlusion
Give an example of formal assessments and informal assessments for hearing aids.
Formal Assessments = hearing evaluation results & self-assessment questionnaires.
Informal Assessments = Observing the pt's communication difficulties & discussing pt's expectations for HAs.
Indicates negative middle ear pressure and possible eustachian tube dysfunction.
Type C
Define immittance measures.
Immittance middle ear measures are based on the measurement of impedance or admittance, so the term immittance was developed to encompass both.
Immittance measures are based on the principle that when a known amount of acoustic energy is delivered to the ear canal, some of the energy is transferred through the ME to the IE, while some of this energy is reflected by the TM.
Describe the process of tympanometry probe measurement from start to finish.
1) A 226 Hz tone is generated by the system and emitted from the loudspeaker.
2) The tone travels from the loudspeaker into the ear canal through the probe tip.
3) Depending on the condition of the ear canal, some of the energy is transmitted (admitted) to the inner ear and some is reflected by the TM.
4) The reflected energy is sent through back to the probe to the microphone.
5) Using this information, the system creates a display of its measurements.
Tympanogram Interpretation Factors
Overall shape of the tympanogram tracing.
Peak admittance (in mmho) of the tymp tracing.
Pressure (in daPa) of peak admittance.
Ear canal volume.
What are factors that negatively impact prognosis for hearing aid success?
1) pt does not perceive a problem
2) pt has too much hearing loss
3) pt has a "difficult" hearing loss configuration
4) pt has very poor speech recognition ability
5) pt has an active disease process in the ear canal