Tympanogram

Question 1

What does a Tympanogram measure?

Answer 1

A graphic representation of admittance with changing air pressure

Assesses how much energy passes into the middle ear

Assesses the movement of the tympanic membrane is in response to changing pressure–but cannot measure directly the TM movement so we measure TM movement by the amount of reflected sound or inversely by the amount of sound passing through the TM to the middle ear.

Question 2

Admittance vs Impedence

Answer 2

Admittance:
How much sound is passing through TM

Impedance:
How much sound is prevented from passing through TM

Question 3

Tympanogram Types

Answer 3

Type A – Normal
+100 and -100 pressure
SC .2 to 3.0

Type As – Reduced Compliance
Static Compliance below 0.2
Normal pressure +100 to -100
Stapes fixation?
Otosclerosis?

Type Ad – Hyper compliance
Compliance greater than 3.0
Disarticulated ossicular chain?
Normal Pressure

Type B – Possible Fluid
Flat structure
Extreme negative pressure in conjunction with reduced compliance
SC < .2
Pressure less than -100

Type C – negative pressure
Pressure below -100 mmho
Normal SC .2 to 3.0