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

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.

[1]  Q Sun,et al.  Computer-integrated finite element modeling of human middle ear , 2002, Biomechanics and modeling in mechanobiology.

[2]  Joubin Hatamzadeh-Tabrizi,et al.  Comparison of Gradient, Gradient Vector Flow and Pressure Force for Image Segmentation Using Active Contours , 2002 .

[3]  Demetri Terzopoulos,et al.  Snakes: Active contour models , 2004, International Journal of Computer Vision.

[4]  Tiong Heng. Siah,et al.  Finite-element modelling of the mechanics of the coupling between the incus and stapes in the middle ear , 2002 .

[5]  Takuji Koike,et al.  Modeling of the human middle ear using the finite-element method. , 2002, The Journal of the Acoustical Society of America.

[6]  W R Funnell,et al.  On the degree of rigidity of the manubrium in a finite-element model of the cat eardrum. , 1992, The Journal of the Acoustical Society of America.

[7]  切替 一郎,et al.  The structure and function of the middle ear , 1960 .

[8]  H. M. Ladak,et al.  On the effects of geometric nonlinearities in a finite-element model of the cat eardrum , 1995, Proceedings of 17th International Conference of the Engineering in Medicine and Biology Society.

[9]  Klaus-Jürgen Bathe,et al.  SAP 4: A Structural Analysis Program for Static and Dynamic Response of Linear Systems , 1974 .

[10]  W. T. Peake,et al.  Input impedance of the cochlea in cat. , 1982, The Journal of the Acoustical Society of America.

[11]  C A Laszlo,et al.  Modeling of the cat eardrum as a thin shell using the finite-element method. , 1978, The Journal of the Acoustical Society of America.