Chapter 1 Study of the Transient Response of Tympanic Membranes Under Acoustic Excitation Morteza Khaleghi, Ivo Dobrev, Ellery Harrington, Cosme Furlong, and John J. Rosowski Abstract Characterization of the transient response of the human Tympanic Membrane (TM) subjected to impulse acoustic excitation is important in order to further understand the mechanics of hearing. In this paper, we present results of our initial investigations of the transient response of an artificial fully-constrained circular membrane as a simplified model of the TM. Two different optical methods used in our investigations are Laser Doppler Vibrometery (LDV) and Pulsed Double- Exposure Digital Holography (PDEDH) for single-point and full-field-of-view measurements of displacements, respec- tively. Applying Hilbert Transformation methods to the measured displacements allows determination of the transient characteristics of the membrane, including damping ratios and time constants, which are also computed and compared with corresponding FEM models. We expect to use this method in the investigation of the transient response of TM of specific species. Keywords Transient response • Laser Doppler Vibrometry (LDV) • Digital holography • Hilbert transform • Tympanic membrane 1.1 Introduction The ear is responsible for translating variations in air pressure, whether from music, speech, or other sources, into the neural activity necessary for our perception and interpretation of sound [1]. The auditory periphery can be broken into three functionally and anatomically distinct components: external, middle, and inner ear, as shown in Fig. 1.1. The primary role of the external and middle ear is to pass the sound stimulus from the environment to the inner ear. The sound wave is diffracted and scattered by the body, head, and ear, and some fraction of the incident sound energy is gathered at the entrance to the ear canal. That sound is transformed as it travels down the roughly cylindrical ear canal to the Tympanic Membrane (TM). The sound acting on the TM sets the ossicles (malleus, incus, and stapes) into motion. The mechanical motion of the ossicles produces a sound pressure and volume velocity of the stapes, in the oval window, at the entrance to the lymph-filled inner ear. The sound pressure and volume velocity in the lymphs within the vestibule M. Khaleghi (*) • I. Dobrev • E. Harrington Center for Holographic Studies and Laser micro-mechaTronics (CHSLT) Mechanical Engineering Department, Worcester Polytechnic Institute, Worcester, MA 01609, USA e-mail: mkm@wpi.edu C. Furlong Center for Holographic Studies and Laser micro-mechaTronics (CHSLT) Mechanical Engineering Department, Worcester Polytechnic Institute, Worcester, MA 01609, USA Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA, USA Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA J.J. Rosowski Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA, USA Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA F. Barthelat et al. (eds.), Mechanics of Biological Systems and Materials, Volume 4, Conference Proceedings of the Society for Experimental Mechanics Series, DOI 10.1007/978-3-319-00777-9_1, # The Society for Experimental Mechanics, Inc. 2014 1