Methodologic observations on tympanometry with regard to the probe tone frequency.

Changes in the tympanogram shape in the frequency range from 200 to 2000 Hz have been investigated. The tympanogram undergoes, as the probe tone frequency rises, characteristic morphologic modifications which are consistently observed both in normals and in some middle ear disorders. The only exception to this regular behavior is the pathological picture in which the structure or the dynamic of the tympano-ossicular system is remarkably anomalous (cholesteatoma and otitis media) where there are flat tympanograms. It is suggested that the frequency interval at which one of the characteristic tympanometric configurations appears in the element capable of furnishing a diagnostic tool for differentiating pathophysiologic conditions of the middle ear.