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The difficulty to estimate the mechanical properties of the tympanic membrane (TM) is a limitation to understand the sound transmission mechanism. In this paper, based on finite element calculations, the sensitivity of the human hearing system to these properties is evaluated. The parameters that define the bending stiffness properties of the membrane have been studied, specifically two key parameters: Young’s modulus of the tympanic membrane and the thickness of the eardrum. Additionally, it has been completed with the evaluation of the presence of an initial prestrain inside the TM. Modal analysis is used to study the qualitative characteristics of the TM comparing with vibration patterns obtained by holography. Higher-order modes are shown as a tool to identify these properties. The results show that different combinations of elastic properties and prestrain provide similar responses. The presence of prestrain at the membrane adds more uncertainty, and it is pointed out as a source for the lack of agreement of some previous TM elastic modulus estimations.

This paper presents the analysis and discussion about different effects of the external auditory canal (EAC) geometry on the response of the human hearing system. Simulation has been made by means of 3D finite element models which included EAC and a model of the ossicular‐eardrum system. Different EAC geometries were constructed, coupled to a middle ear model validated in previous works. The EAC geometry is based on anatomical measurements taken from the literature. The relative position and orientation of the tympanic membrane and section reduction of the canal at the isthmus were studied and analyzed with a harmonic analysis. A sound pressure level of 90 dB was applied at the canal entrance and through fluid‐structure coupling, the pressures in the umbo and the displacements of umbo and stapes footplate were measured in a frequency range from 100 Hz to 20000 Hz.

The study has been developed by means of a FEM of the middle ear. This model was previously validated with experimental data. It is composed by the tympanic membrane, osicular chain, ligaments and tendons support. The cochlear load is simulated with a mechanical equivalent system (damper-mass-damper), and the properties values of materials are taken from the literature according to commonly accepted values [Caminos, 2011]. A sound presure level of 80 dB is applied on the tympanic membrane and the stape footplate velocity is calculated using a harmonic analisys in a frecuency range from 100 to 10 KHz. SVFT is the ratio between the stape footplate velocity and pressure over the tympanic membrane. This parameter is directly proportional to the middle ear acoustic admittance. It is calculated with different values of eardrum Young´s modulus (YM), in the frequency range studied.