tympanometry - exam 2

Question 1

tympanometry

Answer 1

measures the extent to which sound energy is transferred through the outer & middle ear

determined by mobility of the TM as a function of varying pressure in the ear canal

indication of middle ear status

Question 2

why is tympanometry important

Answer 2

determine middle ear function

middle ear disorders risk factors for health, education, &/or development of speech & language

very useful for infants & young children & hard to test populations

Question 3

immittance

Answer 3

impedance, admittance, & compliance

Question 4

acoustic compliance

Answer 4

mobility of the TM in response to air pressure in the ear canal

Question 5

acoustic impedance

Answer 5

the opposition to the flow of sound energy through an acoustic system

inverse of admittance

ohms

Question 6

impedance - mass & stiffness

Answer 6

mass & stiffness of ME system are freq dependent

mass changes have more effect on high freq
stiffness changes have more effect on low freq

ME system is stiffness dominated
low freqs therefore admitted less

Question 7

admittance

Answer 7

the ease w/ which sound energy flows through an acoustic system

inverse of impedance

mmhos

Question 8

basics of measurement

Answer 8

probe tone is introduced into hermetically sealed ear canal

SPL of the signal in the EC is measured - indirect measure of energy passed or opposed

Question 9

high SPL

Answer 9

higher impedance to the flow of energy

lower admittance

Question 10

low SPL

Answer 10

lower impedance to the flow of energy

higher admittance

Question 11

what probe tone do we use for pediatric & adults

Answer 11

226 Hz

because at 226 Hz, mmhos = cm cubed

admittance & volume are interchangeable in our measurements

Question 12

what probe tone for infants (under 3 mos)

Answer 12

1000Hz

ME mechanics different in children than adults

Question 13

plane of measurement

Answer 13

at the probe tip = end of ear canal

ideally want TM because we want measurement of the middle ear not the ear canal

not possible so we must derive it by compensating for the ear canal

Question 14

normal peak admittance for adults

Answer 14

0.37-1.66 mmhos

Question 15

normal peak pressure for adults

Answer 15

-100 -50 daPa

Question 16

normal ECV for adults

Answer 16

0.9-2.0 ml

Question 17

peak admittance

Answer 17

occurs when the pressure on either side of the TM are equal

Question 18

ear canal volume

Answer 18

estimate of volume between probe & TM

in a compensated tympanogram - ECV is given

Question 19

too large ECV

Answer 19

perforation of TM

open PE tube

absence of hermetic seal

Question 20

too small ECV

Answer 20

clogged probe tip

probe tip against canal wall

impacted cerumen

clogged PE tube

Question 21

type A

Answer 21

everything normal

Question 22

type As

Answer 22

shallow

normal peak pressure

reduced peak admittance

increased stiffness, middle ear effusion

Question 23

type Ad

Answer 23

deep

normal peak pressure

higher than normal admittance

scarred or flaccid TM, ossicular discontinuity

Question 24

type B

Answer 24

essentially flat - no peak pressure or admittance

when volume is high - middle ear effusion, cholesteatoma, TM perforation

when volume is low - impacted cerumen or obstruction in EC

Question 25

compensated

Answer 25

compensating for ECV

tails @ 0

Question 26

uncompensated

Answer 26

tails @ ECV

Question 27

Type C

Answer 27

negative pressure peaks beyond -100 daPa

eustachian tube dysfunction, middle ear effusion

Question 28

contra indications for tympanometry

Answer 28

recent surgery

abnormal otoscopic findings
- blood or discharge in the outer ear
- pain upon contact
- otitis external (infection of the outer ear canal/swimmers ear)