Measurement of the Viscoelastic Properties of the Chinchilla Tympanic Membrane

摘要

Tympanic membrane (TM) transmits the sound pressure in the outer ear into mechanical vibration in the middle ear. Quantitate study on the middle ear sound transfer function requires accurate measurements of the TM mechanical properties. In this paper, a dynamic micro-fringe projection technique is developed to measure the viscoelastic properties of the chinchilla TM. An intact TM in the bulla is inflated with a time-varying air pressure. Micro-fringes are projected onto the TM surface during the inflation process and the surface image of the TM is captured with a digital video camera connected to a microscope. The pressure-volume displacement relationship is calculated with a phrase-shift algorithm. Finite element method with the implementation of a viscoelastic model is employed with the pressure history as input. A viscoelastic model is used to model material properties. By solving an inverse problem with the model, the viscoelastic properties of the TM are determined.