Modeling of the human middle ear using the finite-element method

TLDR

A 3‑D finite‑element model of the human middle ear was constructed that incorporates ligaments, tendons, the incudostapedial joint, cochlear loading, the external auditory meatus, and middle‑ear cavities, with mechanical properties and boundary conditions tuned to match measured impedance and validated against tympanic membrane and ossicular motion data. The model, which treats the cochlea as a damper and includes ligaments and tendons, reproduces realistic ossicular chain motion, shows that middle‑ear cavities do not alter tympanic membrane vibration modes, and that the external auditory meatus increases sound pressure at the tympanic membrane without changing its pressure distribution.

Abstract

In this study, a three-dimensional finite-element model (FEM) of the human middle ear was established, including features of the middle ear which were not considered in the previous model, i.e., the ligaments, tendons, I–S joint, loading of the cochlea, external auditory meatus (EAM), middle-ear cavities, etc. The unknown mechanical properties of these parts and the boundary conditions were determined so that the impedance obtained from the FEM analysis resembled the measurement values. The validity of this model was confirmed by comparing the motion of the tympanic membrane and ossicles obtained by this model with the measurement data, and the effects of the newly considered features on the numerically obtained results were examined. By taking the ligaments and tendons into account and assuming that the cochlea acts as a damper, with this model it was possible to realistically reproduce complex ossicular chain movement. It was found that the middle-ear cavities did not affect the vibration mode of the tympanic membrane. Although the EAM enhanced the sound pressure applied to the tympanic membrane compared with that at the entrance of the EAM, the pressure distribution on the surface of the tympanic membrane was not affected by the EAM.