What Is a Tympanometry Test and How Does It Work?

Tympanometry is a short, painless test that checks how freely the eardrum moves. It doesn’t measure how well a person hears. It answers a different question: whether the space behind the eardrum is healthy, or holding fluid or trapped pressure. Most children meet it after failing a hearing screen or having repeated ear infections, because fluid behind the eardrum can muffle hearing without causing any pain. That also means a result that looks normal on a hearing test can still hide a middle-ear problem, and tympanometry is the tool built to find it.

What Tympanometry Measures Behind the Eardrum

Behind the eardrum is a small air-filled space called the middle ear. Three tiny bones there pass vibrations from the eardrum to the inner ear. They act like a lever system, turning the weak vibration of air into a stronger push, which the fluid-filled inner ear needs. The eardrum is the first link in that chain, so if it can’t move freely, the chain starts weaker and less sound gets through, even though the inner ear itself is healthy. That’s why a middle-ear problem can reduce hearing without any damage to the nerve.

The Eustachian tube runs from the middle ear to the back of the nose. It opens to let air in and fluid drain out. When it doesn’t open well, the air in the middle ear is absorbed, pressure drops, and fluid can build up. A cold or allergy flare can swell the tube and leave an ear feeling plugged for days. Children’s tubes are shorter and flatter, so their ears drain less well and fluid collects more often. Flying or diving shows the tube’s job at work: swallowing or yawning makes the ear pop open.

A drum skin vibrates freely only when air sits on both sides of it. Fluid behind the eardrum is like a hand pressed against the drum, dampening the sound. Negative pressure pulls the eardrum inward and tightens it, much like the feeling of an airplane descent. Either way, a stiff eardrum takes in less sound, and hearing is muffled.

The test measures how much sound energy flows into the eardrum and middle ear, not how much travels on to the inner ear.1American Speech-Language-Hearing Association. Tympanometry So it can’t tell you how well you hear, only how well the eardrum and middle ear move.

Fluid behind the eardrum is often painless, unlike an acute ear infection, so a child may show no obvious sign of trouble. Parents tend to notice indirect clues: the TV turned up, repeated “what?”, not responding when called, or seeming inattentive. Young children rarely say their ears feel blocked, so the problem is often found first by a screening test rather than a complaint. Since those signs are easy to put down to attention or mood, an objective test of the middle ear is useful.

How the Test Works Step by Step

A soft-tipped probe seals the ear canal. It holds a speaker, a microphone, and a small air pump. The pump slowly changes the air pressure in the canal while the speaker plays a steady tone, and the microphone measures how much of that tone bounces back instead of entering the eardrum. Most adults and older children are tested with a low 226 Hz tone that sounds like a hum. Young babies are usually tested with a higher 1000 Hz tone, for reasons covered in the accuracy section. The tone is soft and isn’t a hearing check, so nobody has to respond to it.

When the canal pressure differs from the pressure behind the eardrum, the eardrum is pushed against one side and held tighter, so it takes in less of the tone. As the pump sweeps toward the matching point, the eardrum loosens, more sound enters, and less bounces back. The pressure at which the most sound gets in equals the pressure in the middle ear, and that is what the peak of the graph records. With fluid filling the space, the eardrum can’t move freely at any pressure, so there is no clear matching point and the line stays flat.

In adults with negative middle-ear pressure, the eardrum is measurably less flexible than when the pressure is normal.2Ear & Hearing. Effects of Negative Middle Ear Pressure on Wideband Acoustic Immittance in Normal-Hearing Adults The machine reads that stiffness as a lower, shifted peak on the graph.

The machine also estimates the volume of air between the probe and the eardrum, and it does so accurately for typical canal sizes.3PubMed. Assessing the accuracy of tympanometric evaluation of external auditory canal volume: a scientific study using an ear canal model That volume helps separate a healthy ear from one with a hole or a blocked canal.

A good seal matters. The tip can shift as the pressure changes or the person moves, which lets sound leak out. A leak can ruin the reading, so the tester may refit the tip and try again. Talking, chewing, or crying during the few seconds of measuring can also disturb the result.

What Happens During the Appointment

The tester usually looks into the ear first. They are checking for earwax or debris that could block the probe tip or cause a false flat reading. The look also shows whether the canal is open and the eardrum looks intact, and it helps pick the right tip. Tips come in different sizes, and a snug fit at the canal opening is needed for a good seal.

Then the probe goes into the canal opening. You may feel pressure like an airplane descent, along with a low hum. The measurement takes a few seconds per ear, and the result appears at once as a graph called a tympanogram.

You don’t need to do anything. There’s no response to give, so the test works for babies and nonverbal children. There are no drops, and no cleaning beforehand, although heavy wax may need removing first. You can usually go back to normal activity right away.

The test is very safe, and few situations rule it out.4Ascent ENT Speciality Centre. What Is Tympanometry Test and How It Works It may be delayed after recent ear-canal surgery, when pain stops the probe from going in, or when active ear discharge could block the tip.5Ascent ENT Speciality Centre. What Is Tympanometry Test and How It Works

Children who know what to expect and why the test is done are less nervous.6MedlinePlus. Tympanometry: MedlinePlus Medical Encyclopedia Tell your child it’s a quick tickly push of air, with no needles and nothing to answer. Mention that the machine may make a quiet hum so the sound isn’t a surprise. Letting the child watch you take a turn, or trying the probe tip on a toy first, can make the real thing feel familiar.

A parent can usually stay in the room. Sitting a toddler on your lap with a hug calms most of them, and holding them keeps the head steady while the probe is placed. A video or toy keeps the head turned and quiet for the few seconds needed. If a child cries, the tester can wait and retry, since crying changes the pressure readings.

Reading the Results Type A, B and C

The tympanogram falls into a few main patterns, called Type A, B, and C, plus variants such as Type Ad.

On the printout, the horizontal axis shows pressure and the vertical axis shows how freely the eardrum moves. Look at the peak’s height and position and at the printed ear canal volume. Each ear gets its own graph, and results often differ between ears.

With a flat line, check the printed canal volume next, since it helps point to the cause. A normal volume means the eardrum is intact but can’t move well, which usually means fluid behind it.11Interacoustics. Tympanometry: An Introduction A large volume suggests a hole in the eardrum or an open ear tube, because the machine is measuring the middle-ear space too.12Department of Pediatrics. Tympanometry For a child with ear tubes, a large volume and a flat line usually means the tube is open and working. A very small volume with a flat line can instead mean the probe is pressed against the canal wall or blocked by wax, so the test may need repeating.

A peak shifted well into negative pressure suggests the Eustachian tube isn’t opening well.13PubMed Central. Recent Update in the Diagnosis of Eustachian Tube Dysfunction: A Comprehensive Review of the Eustachian Tube Function Test After a cold, that negative pressure often clears on its own over weeks, so doctors commonly recheck after several weeks instead of treating right away. A Type C that persists can lead to fluid buildup, so the follow-up matters.

A very tall peak was long linked to a scarred eardrum or a broken bone chain.14The Egyptian Journal of Otolaryngology. Type Ad tympanogram: is there more than known? But drainage-tube problems can also cause one, and that kind can improve with treatment and recheck.15The Egyptian Journal of Otolaryngology. Type Ad tympanogram: is there more than known?

Type A shows the eardrum moves well and pressure is near normal. It doesn’t measure hearing, so a child with Type A can still have hearing loss from the inner ear or nerve, and a hearing test may still be needed. The range is a guideline rather than a sharp line, and a result near its edge is read together with symptoms and the ear exam.

How Accurate Tympanometry Is

In children having surgery for ear fluid, a flat result correctly identified about 93 of every 100 ears that really held fluid.16Pakistan Journal of Health Sciences. Accuracy of Tympanometry in the Diagnosis of Otitis Media with Effusion in Children’s at Myringotomies: Tympanometry in Otitis Media About 6 in 100 flat results were wrong in that group.17Pakistan Journal of Health Sciences. Accuracy of Tympanometry in the Diagnosis of Otitis Media with Effusion in Children’s at Myringotomies: Tympanometry in Otitis Media A flat result is strong evidence of fluid, but doctors weigh it alongside the ear exam. When a flat line turns out wrong, the cause is usually a poor seal, wax, or a child who moved. That’s why a flat result in a child who seems well is often repeated before a decision is made.

Babies need a different tone. In babies under 12 months, the standard low tone missed about 4 to 6 of every 10 ears with fluid, while a 1000 Hz tone caught nearly all of them.18PubMed. A Comparison of 226- and 1000-Hz Probe Tone Tympanometry With Myringotomy Findings in Infants The reason is that a young baby’s ear canal walls are soft and flexible. They flex with the pressure changes and move like an eardrum would, which adds to the signal and can make a peak appear even when fluid sits behind the eardrum.19PubMed. A Comparison of 226- and 1000-Hz Probe Tone Tympanometry With Myringotomy Findings in Infants The higher tone is less affected by that wall movement, so it shows the middle ear more clearly.

The standard tone isn’t reliable before about 21 weeks of age, and 1000 Hz is preferred.20PubMed. Choice of probe tone and classification of trace patterns in tympanometry undertaken in early infancy Both tones make some mistakes in newborns, but the higher tone makes fewer.21PubMed Central. Tympanometry in Infants: A Study of the Sensitivity and Specificity of 226-Hz and 1,000-Hz Probe Tones

If your baby is tested, ask which tone was used, and expect 1000 Hz for young infants. A normal result with the standard tone in a young baby may not rule out fluid. If hearing concerns continue, ask whether a recheck is planned.

Results can also change from visit to visit. Fluid comes and goes, so one test is a snapshot in time. Colds shift pressure readings temporarily, and a movement or leak during the test can produce a false flat line.

Tympanometry Versus a Hearing Test

A hearing test with headphones measures the softest tones you can hear and helps separate middle-ear from nerve-related hearing loss.22Neotia Mediplus. Key hearing assessment tests: Audiometry, Tympanometry and BERA (Brainstem Evoked Response Audiometry) Tympanometry adds a check that needs no response and shows whether the middle ear is the cause. A hearing test measures the whole hearing pathway, so a mild reduction from fluid can fall within the pass range. Tympanometry sees the middle ear directly, so it can find fluid even when hearing looks near normal. The reverse happens too: normal tympanometry with poor hearing points to the inner ear or nerve rather than the middle ear.

Mild fluid may lower hearing only slightly, so a child can pass a quick screen and still have fluid that affects speech and attention over time. That’s why many clinics run both tests together.

The numbers back this up. In school children, adding tympanometry to a hearing test found ear fluid in 19 ears, compared with 4 found by the hearing test alone.23PubMed. A comparison of audiometry and audiometry with tympanometry to determine middle ear status in school-age children In a school screening program where ear infections were common, adding tympanometry caught about 20% more children with hearing loss.24PubMed Central. Changing the Paradigm for School Hearing Screening Globally: Evaluation of Screening Protocols From Two Randomized Trials in Rural Alaska For children aged 3 to 6, an echo hearing screen combined with tympanometry worked best.25The Hearing Review. The Impact of Adding Tympanometry to Hearing Screenings for Children It’s why a school nurse or clinic may refer a child who passed the hearing part but failed the pressure part.

After an abnormal result, the doctor may examine the ear and do a full hearing test. For fluid, a common plan is to wait and recheck, with ear tubes considered if it lasts. For adults with a blocked feeling, the drainage tube is often the focus.

Newer versions exist as well. Wideband tympanometry tests many tones at once and gives extra detail about middle-ear problems in children.26PubMed. Clinical benefit of wideband-tympanometry: a pediatric audiology clinical study It can help tell apart conditions such as a stiffened or broken middle-ear bone.27PubMed. Wideband absorbance pattern in adults with otosclerosis and ossicular chain discontinuity

Checking the Ear’s Drainage Tube

The peak pressure acts as a stand-in for how well the drainage tube ventilates the ear.28PubMed Central. Recent Update in the Diagnosis of Eustachian Tube Dysfunction: A Comprehensive Review of the Eustachian Tube Function Test Extra versions go further by comparing graphs before and after you swallow with your nose pinched, or blow gently against a closed nose.29PubMed. Tympanometric measures of eustachian tube function A baseline graph is taken with the ear at rest, the probe stays in place while you do the maneuver, and a second graph is taken. A clear pressure shift means the tube opened; little or no change suggests it isn’t opening well. Those two maneuvers produce the clearest shifts, while machine-driven inflate and deflate steps give small, error-prone changes.30PubMed. Tympanometric measures of eustachian tube function On a longer nine-step version, people with worse symptoms tended to show smaller pressure changes.31PubMed Central. Establishment of the Normative Value of Classical Bluestone’s Nine-Step Inflation/Deflation Tympanometric Eustachian Tube Function Test

Adults with plugged ears may be asked to swallow, yawn, or blow gently during testing. A normal test on a good day doesn’t rule out symptoms that come and go, so doctors combine the results with a symptom questionnaire and an ear exam.

Blowing should stay gentle. Hard blowing against a closed nose can force pressure up and make the ear uncomfortable, and a gentle effort is enough to open a working tube. The clinician will guide how much. If you have a cold or a recent ear problem, say so before the test so they can adjust.