Tympanometrie

Tympanometry, sometimes called tympanometrie in non-English texts, is a diagnostic procedure that assesses middle-ear function by measuring the mobility of the tympanic membrane as air pressure in the ear canal is varied. A small probe in the ear canal seals the canal and delivers a probe tone while the pressure is changed. The microphone detects the reflected sound, and the data are plotted as a tympanogram, showing the peak compliance and the corresponding middle-ear pressure.

Technique and scope: The test uses a tympanometer. In adults, a 226 Hz probe tone is standard; in infants, a higher-frequency tone such as 1000 Hz yields more reliable results due to the immature middle ear. Measurements typically span from around +200 to −400 daPa. The procedure is quick, noninvasive, and does not require anesthesia.

Interpretation: Tympanograms are categorized by peak pressure and shape. Type A indicates normal middle-ear pressure and mobility. Type As shows reduced compliance (shallow peak), seen with otosclerosis or tympanic membrane thickening. Type Ad shows hypercompliance (tall peak), associated with ossicular discontinuity or a flaccid tympanic membrane. Type B is flat with no peak, often reflecting middle-ear effusion, tympanic membrane perforation, or cerumen occlusion. Type C shows negative middle-ear pressure with a peak on the negative side, suggesting Eustachian tube dysfunction.

Clinical use and limitations: Tympanometry complements audiometry in assessing conductive hearing loss and middle-ear disease, monitoring treatment, and evaluating readiness for surgery. It is not a standalone diagnostic tool; results can be influenced by cerumen, active middle-ear infection, age, or measurement technique, and must be interpreted with clinical findings.