Mechanical Problems in Human Hearing

For the description of the normal hearing process mechanical models are appropriate and distinct pathological situations can be simulated by changing specific parameters. Nonlinear behavior is found due to nonlinear constitutive equations of the ear drum, the ligaments and the coupling between implant and ossicles as well as due to active processes in the inner ear. Based on multibody system approach models of natural middle ears and reconstructed ears with active implants have been established including some rough assumptions of the nonlinear behavior. To study the dynamic behavior frequency domain methods and time integration has been used. A high risk of damaging the hearing organ of the inner ear is given for loud sound events especially in transient cases. Some measurements in the clinical practice are based on nonlinear effects to detect pathological situations. With simulated multifrequency tympanometry the effect of incudo–stapedial separation on umbo motion is shown. For actively driven implants the effect of different working conditions of the middle ear structure on sound transfer due to prestress in the coupling region has been simulated. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)