The eardrum or Tympanic Membrane (TM) transfers acoustic energy from the ear canal (at the external ear) into mechanical motions of the ossicles (at the middle ear). The acousto-mechanical-transformer behavior of the TM is determined by its shape and mechanical properties. For a better understanding of hearing mysteries, full-field-of-view techniques are required to quantify shape, nanometer-scale sound-induced displacement, and mechanical properties of the TM in 3D. In this paper, full-field-of-view, three-dimensional shape and sound-induced displacement of the surface of the TM are obtained by the methods of multiple wavelengths and multiple sensitivity vectors with lensless digital holography. Using our developed digital holographic systems, unique 3D information such as, shape (with micrometer resolution), 3D acoustically-induced displacement (with nanometer resolution), full strain tensor (with nano-strain resolution), 3D phase of motion, and 3D directional cosines of the displacement vectors can be obtained in full-field-ofview with a spatial resolution of about 3 million points on the surface of the TM and a temporal resolution of 15 Hz.

Date Published: 18 August 2014
PDF: 6 pages
Proc. SPIE 9204, Interferometry XVII: Advanced Applications, 920404 (18 August 2014); doi: 10.1117/12.2063521

Published in SPIE Proceedings Vol. 9204:
Interferometry XVII: Advanced Applications
Cosme Furlong; Christophe Gorecki; Peter J. de Groot; Erik L. Novak, Editor(s)