Tympanometry measures how well your eardrum moves in response to changes in air pressure. It’s a quick, painless test that tells your audiologist or doctor whether the middle ear, the small air-filled space behind the eardrum, is working normally. The results can reveal fluid buildup, pressure problems, eardrum stiffness, or other issues that affect hearing. The whole test takes only a few minutes per ear.
How the Test Works
You sit upright while an audiologist places a small earbud-like probe into your ear canal. The probe creates a tight seal, then does two things simultaneously: it plays a low-pitched tone and gradually changes the air pressure inside your ear canal. As the pressure shifts from positive to negative, the instrument tracks how much of that tone bounces back off your eardrum versus how much passes through it.
A healthy eardrum flexes easily when the pressure on both sides is equal, absorbing most of the sound energy. When the eardrum is stiff, weighed down by fluid, or under abnormal pressure, it reflects more sound back toward the probe. The instrument plots these measurements on a graph called a tympanogram, giving your provider three key pieces of information: the peak movement (compliance) of the eardrum, the pressure inside the middle ear, and the volume of the ear canal.
What the Tympanogram Shows
The graph that prints out after the test has a distinctive shape, and audiologists classify it into types based on that shape. Each type points toward a different set of conditions.
Type A: Normal
A Type A tympanogram shows a clear, sharp peak near zero pressure. This means the eardrum moves freely and the middle ear pressure is balanced. In adults, peak compliance typically falls between about 0.3 and 1.8 units, and normal middle ear pressure ranges from +50 to -100 daPa (the unit used to measure pressure in the ear canal). A result in this range generally rules out fluid or significant middle ear problems.
There are two important subtypes. A Type As result (the “s” stands for shallow) shows a peak that’s unusually low, meaning the eardrum or the tiny bones behind it are stiffer than expected. This can happen when the bones of the middle ear are partially fixed in place or when a small amount of fluid is present. A Type Ad result (the “d” stands for deep) shows an unusually tall, broad peak, suggesting the eardrum or the chain of tiny bones is overly floppy, which can occur with a healed eardrum scar or a disruption in the bone chain.
Type B: Flat
A Type B tympanogram is flat, with no identifiable peak at all. The eardrum is barely moving. The most common cause is fluid trapped in the middle ear, a condition called middle ear effusion. In children, this is frequently tied to ear infections or their aftermath. When a Type B result appears alongside a normal ear canal volume, fluid is the leading suspect. If the ear canal volume is unusually large, it may instead indicate a perforation (hole) in the eardrum, since the probe is essentially measuring the volume of both the ear canal and the middle ear space combined.
Type C: Negative Pressure
A Type C tympanogram still has a peak, but it’s shifted to the left of the graph, into the negative pressure zone. This means there’s a partial vacuum in the middle ear, typically because the Eustachian tube isn’t ventilating properly. The Eustachian tube is a narrow passage connecting the middle ear to the back of the throat, and when it’s swollen or blocked, the air in the middle ear gets absorbed, pulling the eardrum inward. A Type C result often suggests early or developing fluid accumulation, even before the ear feels fully “plugged.”
How Tympanometry Detects Fluid
One of the most valuable uses of tympanometry is confirming or ruling out fluid in the middle ear, especially in children who get frequent ear infections. Studies of patients with confirmed middle ear effusion found a Type B (flat) result in about 43% of cases and a Type C (negative pressure) result in about 47%. That means roughly 9 out of 10 ears with fluid show an abnormal tympanogram.
The test is particularly useful when a doctor looks at the eardrum with a light and sees it isn’t moving well but isn’t sure whether fluid is the reason. A combination of low compliance (below 0.2 mL) and a wide, spread-out tympanogram shape (a gradient greater than 150 daPa) is associated with a 95% or greater likelihood that fluid is present. That level of confidence makes tympanometry one of the most reliable non-invasive tools for this diagnosis.
What the Test Feels Like
Tympanometry is not a hearing test, and it requires almost nothing from you. You’ll feel mild pressure changes in your ear, similar to the sensation of a gentle altitude shift. It’s not painful. The main requirement is that you sit still and avoid talking, swallowing, or moving your jaw during the few seconds the probe is measuring, because any of those actions can briefly open the Eustachian tube and throw off the reading.
Young children are tested the same way, though keeping a toddler perfectly still for even a few seconds can be the hardest part of the process. No sedation or preparation is needed. The probe doesn’t go deep into the ear canal, and there’s no lasting sensation afterward.
Why It’s Done Alongside a Hearing Test
Tympanometry and a standard hearing test answer different questions. A hearing test (audiometry) measures how well you detect sounds at various pitches and volumes. Tympanometry measures the mechanical function of the middle ear, the system that transmits sound from the eardrum to the inner ear. You can have normal tympanometry with hearing loss (if the problem is in the inner ear or auditory nerve), and you can have abnormal tympanometry with hearing that still feels fine (if the fluid or pressure issue is mild).
When the two tests are done together, your provider gets a much clearer picture. If your hearing test shows a loss that’s consistent with a “conductive” pattern, meaning sound isn’t being physically transmitted well, and your tympanogram is flat or shifted, the source of the problem is almost certainly in the middle ear. That distinction matters because middle ear problems are often treatable or temporary, while inner ear hearing loss is usually permanent.
Conditions Tympanometry Helps Identify
- Middle ear effusion: Fluid behind the eardrum, with or without active infection. The most common reason tympanometry is ordered in children.
- Eustachian tube dysfunction: Poor ventilation of the middle ear, producing negative pressure and that familiar “plugged” feeling.
- Eardrum perforation: A hole in the eardrum shows up as a flat tympanogram with an abnormally large ear canal volume.
- Ossicular fixation: Stiffening of the tiny middle ear bones, which produces a shallow (Type As) peak. This can be an early sign of a condition called otosclerosis.
- Ossicular discontinuity: A break in the chain of middle ear bones, producing an unusually tall, floppy (Type Ad) peak.
- Tympanosclerosis: Scarring or calcification of the eardrum from past infections, which reduces its flexibility.
Tympanometry doesn’t diagnose these conditions on its own. It provides a specific, measurable piece of evidence that your provider combines with what they see during an ear exam and what your hearing test reveals. But it’s often the single most informative test for middle ear problems, and its speed and simplicity make it a routine part of nearly every audiology visit.