Tympanograms in ears with small perforations of the tympanic membranes.

It has been believed that in an ear with a perforation, the tympanogram becomes a straight line due to the lack of compliance change in response to the pressure change in the external auditory meatus. Recently, however, we found two types of tympanogram with distinctive characteristics in ears with small perforations. In the first tympanogram type, when the external auditory meatus pressure was changed in the decreasing direction, the compliance peak was formed in the positive-pressure area, whereas it was formed in the negative-pressure area when it was changed in the increasing direction. The difference of the pressure at which compliance peak was obtained was great. The second tympanogram type was unique, with multiple notches similar to those of electronystagmographic recordings of the jerky nystagmus. Knowledge of these tympanograms helps in recognizing small tympanic-membrane perforations.