An introduction to tympanometry

The tympanogram is an objective measure of middle ear effusion or eustachian tube dysfunction. It provides information about the compliance or mobility of the tympanic membrane, the pressure within the middle ear and the volume of the external ear canal. Tympanograms are classified as type A (normal), type B (indicating fluid behind the tympanic membrane) or type C (indicating eustachian tube dysfunction). The objective data obtained by tympanometry are a useful adjunct in the diagnosis and follow-up of middle ear disease.