What tympanometry is
Tympanometry is an objective test of middle ear function. It measures how the eardrum responds to changes in air pressure. Because it does not rely on the person responding, it is useful for babies and young children.
Why it is done
- To check for fluid behind the eardrum (glue ear).
- To assess Eustachian tube function.
- To detect a perforated eardrum.
- To check whether ear tubes (grommets) are open.
- As part of a hearing assessment.
See fluid in ear and Eustachian tube dysfunction.
How the test works
A small, soft-tipped probe is placed in the ear canal to make a seal. The device changes the pressure in the canal from positive to negative while playing a low tone, and a microphone measures how much sound is reflected. The result appears as a graph, the tympanogram.
What to expect
- It takes a few seconds per ear.
- You may feel slight pressure, like going up in a lift.
- It is painless.
- You need to stay still and avoid talking, swallowing or chewing.
- The ear canal is checked first for wax.
Type A: normal
A clear peak near normal pressure shows that the eardrum moves normally and the middle ear is aerated. Two variants give extra information: As (shallow peak) suggests a stiff system, as in otosclerosis or tympanosclerosis, and Ad (very high peak) suggests a very mobile eardrum or a disconnection of the hearing bones.
See tympanosclerosis.
Type B: flat
- Normal canal volume: fluid behind the eardrum, as in glue ear or infection.
- Large canal volume: a perforation or an open grommet.
- Small canal volume: wax blockage or the probe against the canal wall.
See perforated eardrum and ear tubes.
Type C: negative pressure
A peak at negative pressure means the air pressure in the middle ear is lower than outside, usually because the Eustachian tube is not opening properly. It is common with colds, allergies and in children, and may precede glue ear.
See ear won’t pop.
Ear canal volume
The test also measures the volume of the ear canal. Comparing it with expected values helps interpret a flat result: a large volume points to a hole in the eardrum, and a small volume to a blockage.
Acoustic reflexes
Tympanometry equipment can also measure acoustic reflexes, small contractions of a middle ear muscle in response to loud sounds. These help assess the hearing pathway and the facial nerve.
Tympanometry is not a hearing test
Tympanometry shows how the middle ear works but not how well a person hears. It is usually combined with otoscopy and audiometry or age-appropriate hearing tests to give a full picture.
See muffled hearing.
Tympanometry in children
Glue ear is very common in children and may cause hearing loss and speech delay. Tympanometry helps track fluid over time and decide whether watchful waiting, hearing aids or grommets are appropriate.
Tympanometry in young babies
In babies under about 6 months, a higher-frequency probe tone is used because their ear canals are softer and standard results can be misleading.
Limitations
Results can be affected by crying, movement, wax and recent infections. A single test is a snapshot, so tests may be repeated over weeks to see whether fluid clears.
When to see an ENT specialist
- Hearing loss or muffled hearing.
- Ear discharge or persistent pain.
- Speech delay in a child with ear problems.
- Persistent fluid on repeated tests.
- Sudden hearing loss: seek urgent help.
See sudden hearing loss.
Key points to remember
- Tympanometry measures eardrum movement and middle ear pressure.
- Type A is normal; type B suggests fluid or a hole; type C suggests negative pressure.
- It is quick, painless and suitable for all ages.
- It is combined with hearing tests for a full assessment.
Questions about tympanometry
These answers are general information and do not replace an examination or individual medical advice.
What does tympanometry test for?
Middle ear function: fluid, pressure, perforations and ear tubes.
Is tympanometry painful?
No, you may only feel slight pressure.
What does a type B tympanogram mean?
A flat result, often fluid behind the eardrum or a perforation.
What does a type C tympanogram mean?
Negative middle ear pressure, usually Eustachian tube dysfunction.
What is a normal tympanometry result?
Type A: a clear peak near normal pressure.
Is tympanometry a hearing test?
No, it measures middle ear function, not hearing.
How long does tympanometry take?
A few seconds per ear.
What is a tympanometer?
The device used to perform tympanometry.
Can babies have tympanometry?
Yes, with a higher-frequency probe for young babies.
Can wax affect the result?
Yes, wax can block the probe and give a flat result.
Sources
This guide is for general information and does not replace medical advice. How a problem is diagnosed and treated depends on your examination and medical history. If you think you have an emergency, contact your local emergency services.