Influence of different boundary conditions at the tympanic annulus on finite element models of the human middle ear

Abstract

The tympanic annulus is a fibrocartilage ligament that supports the tympanic membrane in a sulcus at the end of the outer ear canal. Among many FE models of the middle ear found in literature, the effect of different boundary conditions at tympanic annulus on middle ear mechanics was not found. In order to investigate the influence of different representations of this detail in FE models, three different ways to connect the tympanic annulus to the outer ear canal were modelled in a reduced middle ear system. This reduced system includes tympanic membrane, tympanic annulus, manubrium, malleus and anterior ligament of malleus. The numerical frequency response function Humbo (umbo velocity vs sound pressure at tympanic membrane) was analyzed through the different boundary conditions and compared to numerical and experimental data from the literature. Also a numerical modal analysis was performed to improve the analysis. It was found that the boundary conditions used to represent the connection between Tympanic Annulus and Outer Ear Canal can change the global stiffness of the system and its natural frequencies as well as change the modal shape of high order modes.The tympanic annulus is a fibrocartilage ligament that supports the tympanic membrane in a sulcus at the end of the outer ear canal. Among many FE models of the middle ear found in literature, the effect of different boundary conditions at tympanic annulus on middle ear mechanics was not found. In order to investigate the influence of different representations of this detail in FE models, three different ways to connect the tympanic annulus to the outer ear canal were modelled in a reduced middle ear system. This reduced system includes tympanic membrane, tympanic annulus, manubrium, malleus and anterior ligament of malleus. The numerical frequency response function Humbo (umbo velocity vs sound pressure at tympanic membrane) was analyzed through the different boundary conditions and compared to numerical and experimental data from the literature. Also a numerical modal analysis was performed to improve the analysis. It was found that the boundary conditions used to represent the connection between Tympan...