Measurement of Stapedial-Footplate Displacements during Transmission of Sound through the Middle Ear

Abstract

The frequency response of stapedial-footplate vibration during sound conduction was measured on fresh cadaver specimens. Specially designed and adapted instruments made these measurements possible at sound levels lower than those causing discomfort to living subjects (84 114 dB), and with a continuous frequency sweep between 100 cps and 10 kcps. The results show a similarity with the curves of subjective ear sensitivity, suggesting a dependence of the over-all sensitivity of the ear on the middle-ear frequency response. Linear increase of vibration amplitude with sound level was found to exist up to around 104 dB; above this sound level, there is a gradual limiting of the stapedial excursions. Speculations on energy transfer from the middle to the inner ear showed nearly optimal matching between them. The influence of the aging process of the specimens is discussed.