Effects of rate of air pressure change on tympanometry.

The effects of two rates of air pressure change upon the pressure and compliance values and classification of tympanograms were determined in normal subjects and subjects with middle ear pathology. Significant differences in the magnitude of compliance and the air pressure corresponding to maximum compliance were observed. The more rapid rate was associated with a higher measured compliance in both groups of ears. In normal ears, the faster pressure change resulted in a shift in the point of maximum compliance toward a more negative pressure, while the reverse was true for ears with middle ear disease. The different rates of pressure change resulted in a different classification of the associated tympanograms for approximately 25% of the impaired ears. These findings imply that the interpretation of the relative normalcy of the tympanogram should take into account the rate of air pressure change used to acquire the result.