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

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.

Low-Frequency Finite-Element Modeling of the Gerbil Middle Ear

“…Given the lack of measurements on the mechanical properties of the pars flaccida (PF), Koike et al (2002) assumed that the Young_s modulus of the PF is one-third of that of the PT. Using the same ratio, we set the Young_s modulus of the PF to 20 MPa.…”

“…A final value of 80 GPa was obtained, beyond which the displacements throughout the model would change by less than 3%. By comparison, in recent finite-element models, the Young_s modulus for human ossicles was taken to be 14.1 GPa (Prendergast et al 1999;Sun et al 2002) based on Speirs et al (1999), who measured the Young_s modulus of human ossicle allografts using axial compression; and 12 GPa (Koike et al 2002) based on a review by Evans (1973).…”

“…To date, no experimental measurements of the elastic properties of the middle-ear ligaments have been done. Other research groups have fitted their models to experimental data to determine the Young_s modulus of the ligaments (Prendergast et al 1999;Koike et al 2002;Sun et al 2002). In this study, the Young_s moduli of the AML and of the PIL were set to 20 MPa as a reasonable value for dense connective tissue, as used in previous models from our laboratory (Ghosh and Funnell 1995;Funnell and Decraemer 1996;Ladak and Funnell 1996;Funnell et al 1999Funnell et al , 2000.…”

“…A number of groups have since used the finiteelement method to study the mechanics of the eardrum and ossicles in humans (Wada et al 1992;Beer et al 1999;Bornitz et al 1999;Prendergast et al 1999;Koike et al 2002;Sun et al 2002) and in cats (Funnell and Laszlo 1978;Funnell et al 1987;Ladak and Funnell 1996;Funnell et al 2005). The geometries have generally been oversimplified and material properties have often been based on curve fitting.…”

Experimental and Modeling Study of Human Tympanic Membrane Motion in the Presence of Middle Ear Liquid

“…Sound-induced TM vibration has been measured at the umbo using laser Doppler vibrometry (LDV) (Goode 1994;Whittemore et al 2004;Gan et al 2004a;2006b;Dai et al 2007Dai et al , 2008Rosowski et al 2003Rosowski et al , 2008 and analyzed using finite element (FE) models of the ear (Funnell et al 1987;Puria and Allen 1998;Koike et al 2002;Sun et al 2002;Gan et al 2004bWang et al 2007;Zhang and Gan 2011). However, single-point measurements cannot provide information about complex TM surface motion and the properties of sound wave propagation across the TM.…”