Viscoelastic properties of tympanic membrane are critical input for modeling acoustic transmission in hearing system. The viscoelastic properties of a human eardrum or tympanic membrane have not been fully characterized in the auditory frequency range, despite the fact that these properties are critical input in modeling the acoustic transmission in a human ear. Using a miniature split Hopkinson tension bar (SHTB), we investigated the mechanical behavior of tympanic membrane at high strain rates, corresponding approximately to the behavior at high frequency. The results indicate that normal human TMs show stronger dependence on high strain rates. The measured Young's modulus is converted into complex Young's modulus in the frequency domain in the frequency range of 300-2000 Hz. In the second part of the presentation We describe a method to measure the mechanical properties of tympanic membrane in its intact form. A stereo microscope is used to observe the tympanic membrane under either positive or negative pressures. The three-dimensional digital image correlation technique was used to determine both the surface topography and full-field three-dimensional surface deformations. A finite element model is established to model the full-field deformations. The material constitutive model parameters are tuned to allow simulation results to agree with three dimensional deformation field to allow determination of the properties of the tympanic membrane.
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