Abstract
Hearing loss is highly related to acoustic injuries and mechanical damage of ear tissues. The mechanical responses of ear tissues are difficult to measure experimentally, especially cochlear hair cells within the organ of Corti (OC) at microscale. Finite element (FE) modeling has become an important tool for simulating acoustic wave transmission and studying cochlear mechanics. This study harnessed multiscale FE models to investigate the mechanical behaviors of ear tissues in response to acoustic wave and developed a fatigue mechanical model to describe the outer hair cells (OHCs) failure. The three-dimensional multiscale FE models consisted a macroscale model of the ear canal, middle ear, and 3-chambered cochlea and a microscale OC model on a representative basilar membrane section, including the hair cells, membranes, and supporting cells. Harmonic Acoustic mode was used in the FE models for simulating various acoustic pressures and frequencies. The cochlear basilar membrane and the cochlear pressure induced by acoustic pressures were derived from the macroscale model and used as inputs for microscale OC model. The OC model identified the stress and strain concentrations in the reticular lamina at the root of stereocilia hair bundles and in the Deiter's cells at the connecting ends with OHCs, indicating the potential mechanical damage sites. OHCs were under cyclic loading and the alternating stress was quantified by the FE model. A fatigue mechanism for OHCs was established based on modeling results and experimental data. This mechanism would be used for predicting fatigue failure and the resulting hearing loss.
