Eiber Albrecht
Institute of Engineering and Computational Mechanics, University of Stuttgart Pfaffenwaldring 9, 70550 Stuttgart, Germany.
Stud Health Technol Inform. 2008;133:83-94.
A description of the hearing process is given using three-dimensional mechanical models. By means of simulation, normal, pathological and reconstructed situations can be investigated. The development of new concepts and prototypes as well as the optimization and the way of insertion of passive and active implants is facilitated by carrying out virtual tests. Mechanical models of spatial structures of the middle ear and its adjacent regions are established by applying multibody systems and finite element modeling approach. In particular, the nonlinear behavior of the elements is taken into account. For the determination of parameters such as coupling parameters in reconstructed ears, measurements using Laser Doppler Vibrometry (LDV) were carried out. The governing differential equations of motion allow the investigation of transient and steady state behavior by time integration and frequency domain methods. Optimization methods can be applied for determination of design parameters such as coupling stiffness and damping, the characteristics of actuator, the position of attachment and direction of actuation. Mechanical models enable non-invasive interpretation of dynamical behavior based on measurements such as LDV from umbo or multifrequency tympanometry. It is shown: The transfer behavior is depending on static pressures in the ear canal, tympanic cavity or cochlea. For reconstructed ears, the coupling conditions are governing the sound transfer substantially. Due to restricted coupling forces, the excitation of inner ear is limited and the sound transfer is distorted. Other sources of distortion are nonlinear coupling mechanisms. In reconstructions with active implants, the actuator excites the microphone whereby feedback effects may occur.
利用三维力学模型对听力过程进行了描述。通过模拟，可以研究正常、病理和重建情况。通过进行虚拟测试，有助于新概念和原型的开发以及被动和主动植入物的优化和植入方式。应用多体系统和有限元建模方法建立了中耳及其相邻区域空间结构的力学模型。特别地，考虑了元件的非线性行为。为了确定重建耳中的耦合参数等参数，使用激光多普勒测振仪（LDV）进行了测量。运动控制微分方程允许通过时间积分和频域方法研究瞬态和稳态行为。优化方法可用于确定设计参数，如耦合刚度和阻尼、致动器特性、附着位置和驱动方向。力学模型能够基于来自鼓膜脐部的LDV测量或多频鼓室图等测量对动态行为进行非侵入性解释。结果表明：传递行为取决于耳道、鼓室或耳蜗中的静压。对于重建耳，耦合条件基本上控制着声音的传递。由于耦合力受限，内耳的激发受到限制，声音传递发生畸变。其他畸变源是非线性耦合机制。在有源植入物的重建中，致动器会激发麦克风，从而可能产生反馈效应。
