Ear drum mobility and middle ear volume measured with tympanometry.

Abstract

Tympanometry was evaluated as a measure of the volume of the air-containing space of the middle ear cleft as well as of tympanic membrane displacement in persons with intact tympanic membranes. Static compliance reduced with compliance of ear canal volume at -400 mm H2O, was determined with 0.22 kHz probe tone frequency. Further the difference in compliance obtained at +/- 400 mm H2O was regarded as a measure of ear drum mobility. The volume of the middle ear cleft including the mastoid air cell system was measured indirectly by X-ray of the ear in a lateral projection. No relation was found to exist between static compliance and mastoid air cell area measured on the X-ray film. Nor was there any relation found between ear drum mobility measured with tympanometry and size of the mastoid air cell system.