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How does tympanometry evaluate the eardrum and middle ear?

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Tympanometry is a diagnostic procedure used to evaluate the condition of the tympanic membrane (eardrum) and the middle ear. It is particularly useful for identifying middle ear issues, such as the accumulation of fluid in children prone to ear infections.1

The procedure functions on the principle that sound entering the ear canal is partially reflected by the eardrum. During the test, a handheld instrument produces a pure tone while simultaneously altering the air pressure within the ear canal. A sensitive microphone measures the amount of sound reflected back from the eardrum.1

When the eardrum becomes stiff—often due to middle ear conditions or fluid buildup—it reflects more sound. By measuring these changes in compliance as air pressure is varied, clinicians can identify conductive defects, such as the immobility of the ossicles or disarticulation of the ossicular chain.12