Influence of middle ear cavity wall absorption on mechanics of hearing

Influence of middle ear cavity wall absorption on mechanics of hearing

conference paper

Czech

Impedance and wall absorption are important characteristics of acoustical systems. Unlike the electrical case, no convenient commercial system is available for acoustical impedance measurement. Reasons for this lack include the unavailability of low distortion acoustic sources, the unavailability of precisely calibrated acoustic sources, and the complications introduced by the wave-like nature of sound (due to the relatively slow sound speed). Therefore it is an absence of serious experimental data of eardrum acoustic impedance or ear cavity wall impedance. In this paper we shall discuss an application of mathematical modelling for the determination of an interval of possible impedance values. The modelling used here is based on final element method (system Ansys 7.1), the complete mechanical model of human ear. From the point of view of acoustic energy transmission are taken in account the acoustic subsystem of the external auditory canal, the elastic structure of the tympanic membrane, the middle ear cavity acoustic subsystem, the stiff ear ossicle chain with moveable joints, the coupling of individual ossicles to the walls of middle ear cavity via ligaments and muscles and the coupling of stapes footplate to oval window (the enter of cochlea).

Impedance and wall absorption are important characteristics of acoustical systems. Unlike the electrical case, no convenient commercial system is available for acoustical impedance measurement. Reasons for this lack include the unavailability of low distortion acoustic sources, the unavailability of precisely calibrated acoustic sources, and the complications introduced by the wave-like nature of sound (due to the relatively slow sound speed). Therefore it is an absence of serious experimental data of eardrum acoustic impedance or ear cavity wall impedance. In this paper we shall discuss an application of mathematical modelling for the determination of an interval of possible impedance values. The modelling used here is based on final element method (system Ansys 7.1), the complete mechanical model of human ear. From the point of view of acoustic energy transmission are taken in account the acoustic subsystem of the external auditory canal, the elastic structure of the tympanic membrane, the middle ear cavity acoustic subsystem, the stiff ear ossicle chain with moveable joints, the coupling of individual ossicles to the walls of middle ear cavity via ligaments and muscles and the coupling of stapes footplate to oval window (the enter of cochlea).

FEM, muman ear, harmonic analysis

DUŠEK, D., PELLANT, K.

2005

9. 5. 2005

Institute of thermomechanics, AS CR

Praha

80-85918-93-5

Book of extended abstracts

75

76

2