Tympanometry - Procedure, Uses, and Interpretation — Procedure Guide, Recovery & Risks | MyMedicPlus

Tympanometry is a rapid, objective, non-invasive diagnostic test used in audiology and otolaryngology to evaluate the mechanical compliance of the tympanic membrane (eardrum) and middle ear system by measuring acoustic impedance — the resistance of the middle ear to the passage of sound energy — as a function of air pressure applied to the sealed external ear canal. The test produces a graphical output called a tympanogram, which plots middle ear compliance (in millilitres or decaPascals) against applied air pressure (in decaPascals, ranging from -400 to +200 daPa). The shape and peak characteristics of the tympanogram provide specific diagnostic information about the status of the middle ear space, tympanic membrane integrity, Eustachian tube function, and ossicular chain continuity. Tympanometry is classified by the Jerger classification system into Types A (normal), B (flat — middle ear effusion or perforation), C (peak shifted negative — Eustachian tube dysfunction or early effusion), As (shallow — ossicular chain stiffness, e.g., otosclerosis), and Ad (deep — ossicular chain discontinuity or flaccid tympanic membrane). It is a cornerstone investigation in the diagnosis of otitis media with effusion (glue ear) — one of the most common childhood disorders requiring medical or surgical management — and is used routinely in neonatal hearing screening programmes, adult hearing assessment, and post-surgical hearing monitoring. The test takes 30-60 seconds and requires no patient cooperation beyond remaining still.

Tympanometry is indicated whenever middle ear pathology is suspected, needs to be confirmed, or requires monitoring over time. Common clinical indications include evaluation of children with suspected otitis media with effusion (glue ear) — characterised by hearing loss, speech delay, frequent ear infections, or language development concerns — where a Type B tympanogram (flat curve, low compliance) confirms the presence of middle ear fluid. In adults, tympanometry is indicated for persistent conductive hearing loss detected on audiometry, ear fullness or pressure sensation suggesting Eustachian tube dysfunction, hearing loss following acute otitis media that has not resolved after 8-12 weeks, and assessment of tympanic membrane integrity after acute perforation or in follow-up after myringoplasty surgery. Tympanometry is a mandatory component of neonatal hearing screening programmes in many countries, helping identify congenital conductive hearing loss due to middle ear effusion or structural abnormality from birth. Adults with workplace noise-induced hearing loss or those fitted with hearing aids undergo regular tympanometry to monitor for middle ear pathology that might affect hearing aid fitting or performance. Post-grommet (ventilation tube) insertion monitoring uses tympanometry to confirm adequate drainage and tube patency.

The audiologist inspects the ear canal with an otoscope to confirm no wax occlusion or perforation before proceeding. A small rubber probe tip of appropriate size is selected and placed snugly into the ear canal to create an airtight seal. In adults, a 226 Hz probe tone is used; in infants under 6 months, a 1000 Hz tone is preferred as it provides more reliable results at this age. The tympanometer automatically sweeps the air pressure from +200 to -400 decapascals (or in the reverse direction) while continuously measuring the acoustic admittance at the probe. The entire sweep takes approximately 2–3 seconds per ear. The resulting tympanogram is displayed on screen and printed. Three main patterns are recognised: Type A (normal peak at 0 daPa, compliance 0.3–1.6 mL), Type B (flat curve indicating effusion, perforation, or wax blockage), and Type C (negative peak beyond -100 daPa indicating Eustachian tube dysfunction and negative middle ear pressure). The full test including explanation and documentation takes 5–10 minutes per patient. Multi-frequency tympanometry assesses middle ear compliance at multiple probe tone frequencies (226, 678, and 1000 Hz), improving diagnostic accuracy for ossicular pathology and middle ear effusion differentiation in infants and neonates, in whom 226 Hz tympanometry lacks sensitivity due to the compliance characteristics of the soft neonatal ear canal.

Tympanometry is painless, rapid, and requires no patient cooperation or radiation, making it uniquely suited to all age groups including neonates. It accurately identifies middle ear effusion with over 90% sensitivity and specificity, enabling confident diagnosis of glue ear without the need for imaging. A Type A result effectively excludes middle ear pathology. The objective nature of the test eliminates observer-dependent variability seen with otoscopy alone, which has poor interrater reliability for identifying effusion. Tympanometry quantifies the degree of middle ear dysfunction, guides treatment decisions — including the timing of grommet insertion — and objectively monitors treatment response. It adds critical discriminatory information when interpreting audiometry results, distinguishing conductive from sensorineural hearing loss. The test is inexpensive, portable, and can be performed in community audiology and primary care settings.

Tympanometry is extremely safe with no significant risks when performed on an intact eardrum. The primary contraindication is a known or suspected tympanic membrane perforation — pressure changes could push debris or infective material into the middle ear, causing pain and potential further damage. The test should be postponed if a grommet (tympanostomy tube) is in situ, as the tube prevents a sealed system and produces a Type B pattern regardless of middle ear status. Airtight seal cannot always be achieved in ears with severely narrow, collapsing, or wax-occluded canals. In young infants, a 226 Hz probe tone can produce unreliable or misleading results due to the highly compliant cartilaginous canal; specialist 1000 Hz equipment is required. A Type B tympanogram cannot differentiate between middle ear effusion, eardrum perforation, and cerumen impaction without clinical correlation.

No recovery period is required following tympanometry. The test is entirely non-invasive and patients may return to normal daily activities immediately. Mild transient discomfort from the ear canal probe tip is the only expected sensation, resolving as soon as the probe is removed. Results are interpreted immediately by the audiologist. A Type A tympanogram with normal peak compliance confirms intact middle ear function. Type B findings in the context of hearing loss and clinical features strongly support a diagnosis of otitis media with effusion. Type C patterns indicate impaired Eustachian tube function and often respond to nasal decongestants or watchful waiting. Referral pathways depend on the combination of tympanometry result, audiometry findings, and clinical presentation. Follow-up tympanometry is commonly scheduled at 4–6 weeks to reassess resolution of middle ear effusion before considering surgical intervention.