FUNCTION OF THE ROUND WINDOW IN HEARING

Abstract

In 11 trained dogs, whose normal thresholds of hearing had been accurately measured, the bullae acusticae were opened. Gum-gauze pledgets were gently worked into the fossulae rotundae and thus brought into direct opposition with the secondary tympanic membranes. In every case insertion of these plugs impaired, and withdrawal restored hearing, the mean difference in scores being almost 10 decibels. These observations indicate that damping, weighting or immobilizing the round-window membranes definitely impairs the efficiency of cochlear function. The acoustic significance of a given phenomenon can be demonstrated only by actual tests of hearing; such acoustic value cannot be assumed merely because that phenomenon has been observed in connection with the middle ear, cochlea or 8th nerve.