HIGH-SPEED DIGITAL HOLOGRAPHIC METHODS TO CHARACTERIZE THE TRANSIENT ACOUSTO-MECHANICAL RESPONSE OF HUMAN TM

Human hearing relies on a delicate sequence of energy transformations from the sound waves in the outer-ear, through mechanical vibrations in the middle-ear, to pressure waves of the fluid in the inner-ear. The investigation of hearing process requires the study of the function of the tympanic membrane (TM) in the energy transformation at the interface of the outer and middle-ear. The investigation of this process requires tools to quantify the acousto-mechanical response of the TM while overcoming the challenges associated with its dimensions, confined location, and the high temporal and spatial complexity of its nanometer scale motions that also relate to its internal multi-layer fiber structure. In this paper, we report our current efforts in the development and implementation of digital holographic methods for high-speed (i.e., >25,000 fps) and high temporal resolution (i.e., <10μs) full-field-of-view characterization of the TM response to transient acoustic excitations, including measurements of associated time-constants and damping characteristics. The result of this work may lead to a more detailed understanding of the acousto-mechanics of the TM and its role in the hearing process.