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Acousto-mechanical response of the human tympanic membrane measured by high-speed digital holography

Ivo Dobrev (Worcester Polytechnic Institut), Cosme Furlong (Worcester Polytechnic Institute), John Rosowski (Massachusetts Eye and Ear Infirmary), Jeffrey Cheng (Massachusetts Eye and Ear infirmary)

Joint Session: Mechanics of cell sheets, multicellular assemblies and tissues and Mechanics and Physics of Biological Cells

Mon 2:40 - 4:00

Barus-Holley 141

We are developing digital holographic methods to quantitatively measure the acousto-mechanical responses of the human tympanic membrane (TM) in-vivo to help in the diagnosis and treatment of common hearing losses. To achieve such measurements we have to overcome important technological challenges imposed by the dimensions of the TM, its confined location, and the disturbances produced by the patientís heartbeat, breathing, as well as environmentally induced vibrations. In addition, the amplitudes of the motions induced by acoustic excitation of the TM are in the order of nanometers while the external disturbances are of several orders of magnitude larger. With our holographic methods we are able to perform measurements at high speeds (i.e., > 25,000 fps) and in full-field-of-view with nanometer scale resolutions to be able to quantify the acoustic steady state and transient responses of the TM. Holographic systems have been deployed in the clinic for in-vitro measurements and are being further optimized for measurements in-vivo. We present our work on the design and implantation of acquisition and measurement methods to quantify the low amplitude (i.e., < 0.5 m) high frequency (i.e., 0.2 Ė 20 kHz) sound induced vibrations of the TM in the presence of high amplitude (i.e., > 500 Ķm) external disturbances. We also present our work on the design and implementation of high-speed and high temporal resolution (i.e., < 10 s) acquisition and measurement methods for quantification of the TMís transient mechanical parameters such as time-constants, damping and quality factors.