Perforation of the Tympanic Membrane and Haring Loss

One hundred and fifteen cases with the traumatic tympanic membrane (T. M) perforations were investigated in order to estimate the effect of perforation on hearing. The following statistical results were obtained, though the cases showed wide variations of audiograms. (1) A large perforation caused larger hearing loss than a small perforation. (2) The anterior large perforation produced hearing loss which increased inversely with frequency below 1kHz, however the posterior large perforation did not show such tendency. (3) The anterior large perforations reached the manubrium of the malleus produced more hearing loss in high frequencies above 1kHz than the anterior large perforations not extended to the malleus. (4) The average losses for small perforations was minimal and frequency independent. These results were not explicable only by “physicoacoustical factor” such as the lost baffle effect, thus “physiologicoacoustical factor” such as the vibratory characteristics of the T. M. should be taken into consideration.