A study of transfer function of human middle ear by bone conduction

Abstract

Vibration of tympanic membrane induced by sound is transmitted to a cochlea via middle-ear ossicular chain and stimulates an auditory nerve. Hearing sensation produced by sound is described as air conduction. Vibration of a skull induced by vocal sound is also transmitted to a cochlea. Hearing sensation produced by vibration of a skull is described as bone conduction. Therefore, human vocal sound is perceived by means of two pathways, air and bone conduction. In the present study, the roll of the ossicular chain of bone conduction is analyzed numerically by using a technique of multibody dynamics. The numerical model of the ossicular chain is created precisely by using pictures of computerized axial tomography scan. The vibrational responses of the ossicular chain and the force transmitted to a cochlea induced by the stimuli of air and bone conduction ware calculated. The magnitude of the force induced by the bone conduction was about one third of that induced by the air conduction.