Middle-ear Finite-Element Modelling with Realistic Geometry and a Priori Material-Property Estimates

Abstract

 Finite-element models of the middle ear have generally included oversimplified geometries, and many of their material properties have often been estimated by curve fitting to averaged experimental vibration measurements from multiple ears. As a result, the parameter values may not be physiologically reasonable. Our study aims to construct a valid middle-ear finite-element model without such curve fitting by (1) creating realistic geometries, and (2) using a priori estimates for the material properties. 

  We began by scanning a human temporal bone using x-ray microcomputed tomography. Details of middle-ear structures were then segmented, both manually and semi-automatically. The substructures were assigned appropriate material properties – including thickness, Young’s modulus, and Poisson’s ratio – based on a detailed literature review, and a finite-element model was generated.

  The static behaviour of this model was compared with lowfrequency measurements performed on the same temporal bone using laser Doppler vibrometry. Preliminary results show good model accuracy with regard to footplate and eardrum displacements, and agreement within a factor of about two for umbo displacement. A sensitivity test was done to identify those material properties which have strong effects on the model behaviour.