Acoustic Immittance Flashcards
Acoustic immittance tests:
middle-ear function
Does acoustic immittance require a response from the patient?
No.
Acoustic immittance measurements help us to differentiate different types of _____________ disorders
Conductive
What can acoustic immittance identify?
A medically significant middle ear disorder that can be present without an air-bone gap evident in the audiogram
(T/F) Acoustic immittance measurements can be obtained during other tests.
FALSE. Acoustic immittance measurements yield information that cannot be obtained any other way.
What information does acoustic immittance tests provide?
Eardrum and middle ear problems
Differentiates type of disorder: conductive vs. cochlear vs. retrocochlear
Conformation of the pure tone audiometric results in terms of the type of less and an estimate of hearing sensitivity
Integrity of the facial nerve on the efferent pathway of the acoustic reflex arc.
What test is performed for acoustic immittance?
Tympanometry
What three acoustic reflexes are tested in acoustic immittance?
Ipsilateral
Contralateral
Reflex Decay
a term that refers collectively to acoustic impedance, acoustic admittance, or both
Acoustic immittance
The opposition to sound flow measured in acoustic ohm (obstruction to the flow - restricting)
Acoustic impedance
The easy with which sound flows measured in acousic mmhos (no opposition to flow - not restricting)
Acoustic admittance
Impedance and admittance are __________ terms.
reciprocal
What is the term for acoustic admittance measures
Ya (Y sub a)
What are the four tubes and what do they do in a tympanogram?
- Probe tip loudspeaker - presents a continuous tone (226 Hz at 85 dB SLP)
- Monitor Microphone - picks up reflected sound in the ear canal
- Pressure pump and manometer - pressure variation
- Ipsilateral reflex loudspeaker
Involves measuring the acoustic admittance of the ear with various amount of air pressure in the ear canal
Tympanometry/Tympanogram
Acoustic admittance is measured and plotted on a graph called a ________________.
tympanogram
What happens during a tympanogram?
A hermetic (airtight) seal is created at the opening of the ear canal by inserting an ‘ear plug’ into the opening of the ear canal
A tone of 226 Hz is generated by the loudspeaker
Air pressure is varied by the air pump
Reflection of sound is picked up by the microphone
The pressure within the ear canal is reduced below atmospheric pressure and a low-frequency tone is presented at 85 dB SPL continually
What are the five calculations that can be made from a tympanogram?
- Peak Ya - measurement plane tympanogram
- Peak Ytm - peak compensated static acoustic admittance (mmhos); compensated tympanogram
- TPP - tympanometric peak pressure (daPa)
- TW - tympanometric width (daPa)
- Vea/Vec/ECV - ear canal volume in cm^3
the total acoustic admittance (mmhos) at the peak
Peak Ya
(T/F) at the extreme high and low pressure levels, the Peak Ya is at zero.
False. It is not at zero because the ear canal itself offers a small degree of acoustic admittance
the contribution of the tympanic membrane alone
Peak Ytm
What is the unit of measurement for acoustic impedance?
acoustic ohm
What is the unit of measurement for acoustic admittance?
acoustic mmhos
In a tympanogram, which tube deals with pressure variation?
Pressure pump and manometer
In a tympanogram, which tube deals with picking up reflected sound in the ear canal?
Monitor microphone
In a tympanogram, which tube presents a continuous tone at 226 Hz, 85 dB SPL?
Probe tip loudspeaker
What is the formula for Ytm?
Ytm = Ya(peak) - Ya(tail)
The pressure at which Ya or Ytm is at its maximum value in daPa
TPP (tympanometric peak pressure)
the width of the tympanogram at 1/2 the high of Ytm (peak to tail)
TW (tympanometric width)
an acoustic estimate of the volume between the probe tip and the tympanic membrane - estimated from Ta at high or low pressure levels
Vea/Vec/ECV - ear canal volume
Large ear canal = _______ volume
High
Small ear canal = _________ volume
Low
What are the normal ear canal measurements for children (3-10)?
Peak Ytm - .25-1.05
TW - 80-159
Vea - .3-.9
What are the normal ear canal measurements for adults (>18)?
Peak Ytm - .30-1.70
TW - 51-114
Vea - .9-2.0
In a stiff ear, there is _________ admittance, ________ impedance.
low admittance
high impedance
If there is negative middle-ear pressure, the result is _________ admittance, ________ impedance.
low admittance
high impedance