In The Ears Of The Ossicular Chain Of Finite Element Modeling Of The Mechanical Mechanism Of Sound Conduction

The ossicular chain in the middle ear is a typical dynamic system.Building up the finite element model of the ossicular chain helps to expound the mechanical mechanism of sound transmission.It can provide complete mathematical model and research platform for assessing the influence of diseases on hearing and can also be used to guide the clinical treatment of hearing loss.This paper constructed the geometrical surfaces of the middle ear including the tympanic membrane,three ossicles(malleus,incus and stapes),their suspensions by ligaments and tendons using the pictures from the serial tissue sections and Micro-CT scanning of the human temporal bone.The finite element modeling,analysis and validation were carried out on the base of this model.Firstly,during the process of geometrical integration,the effect of the joint state between the incus and the stapes to the sound transmission in the middle ear was first time analyze.This study can support necessary basis to build up the reasonable geometrical model.Secondly,the paper performed the reasonable hypothesis and simulation to the exterior and interior boundaries of the middle ear finite element model.An efficient and high precision method using mixed element of the quadrangle element and triangle element was introduced into the mesh of eardrum.The lymph fluid of cochlea could be equivalent to mass-stiffness-damping model based on the physiological characteristics of lymph fluid,the physical parameters of the equivalent model were determined according to the published physical properties.Thirdly,the paper analyze and validated the finite element model of tympanic membrane and the whole middle ear system.After the static and dynamic analysis to the tympanic membrane the results were compared with the published data and the reliability based on the mixed element eardrum model was verified.The natural frequencies of system were compared with the result of the LDV vibration test.The reliability of the FE model was confirmed by the comparison.Finally,a further research by changing the physical parameters of equivalent model was then made to observe the effect of lymph fluid on the sound transmission. The vibration motions of stapes footplate were also observed.