lec 3 Flashcards
which structures does tympanometry measure the function of? (3)
measures function of TM, middle ear, ET indirectly.
what is admittance vs impedance?
- admittance: ease with which energy will flow through a vibrating system (high admittance = high compliance).
- impedance: extent to which a system resists the flow of energy through it (high impedance = low compliance).
T or F: eardrum vibrates most efficiently when pressure is equal on both sides of it
true
T or F: a tone introduced into the ear canal of a healthy ear will have lots of sound bouncing back
false – minimal sound bouncing back
what does a tympanogram measure?
measures change in compliance as a function of air pressure change in ear canal.
what are type A tymps?
- type A: point of greatest compliance is around 0 daPa (normal)
- type As: pressure normal, compliance low
- type Ad: pressure normal, compliance high
what can cause very high compliance?
broken ossicles
who has type A tymps? (2)
- typical hearing
- sensorineural hearing loss
what are type B tymps?
no point of greatest compliance (flat)
who has type B tymps? (4)
- conductive or mixed hearing loss
- TM perforated
- open ear tube
- blocked probe tube
what are type C tymps?
point of max compliance occurs when negative pressure is put into the ear canal (middle ear is negative)
who has type C tymps? (2)
- conductive or mixed hearing loss
- ET dysfunction
T or F: all type C tymps have ET dysfunction, but not all people w/ ET dysfunction have type C tymps
true
what is the range of static compliance values (peak heights) for type A and C tymps and what do they mean?
- normal: 0.3-1.5 cc
- smaller: less mobility
- larger: greater mobility
what are the ranges for normal vs high vs low ear canal volumes (ECV)? which tymp type do we care about ECV?
- normal: 0.4-2 cm3
- high: > 2 cm3
- low: < 0.4 cm3
- type B tymp
