Photonic Devices and the Biomechanics of Hearing

Lecture / Panel
For NYU Community

Joint Seminar: Department of Electrical & Computer Engineering and Department of Mechanical & Aerospace Engineering

5/4 (Monday)    Noon – 1:00 pm     RH202

Photonic Devices and the Biomechanics of Hearing

Sunil Puria, Ph.D.
Department of Mechanical Engineering and
Department of Otolaryngology
Stanford University

The broad frequency ranges unique to mammalian hearing provide an important means of localizing sound, which in turn enables humans to understand speech in noisy environments. However, this ability is reduced among hearing-impaired listeners, since hearing aids typically only provide amplification up to about 5 kHz. I will describe an extended-bandwidth non-surgical hearing-aid design in which light is used to wirelessly transmit both the power and signal to a tiny micro-actuator placed in direct contact with the eardrum. Results from a multi-site FDA-approved clinical trial indicate that the unprecedented 0.2–10 kHz frequency range of this device enables hearing-impaired subjects to perceive acoustic cues that greatly enhance sound quality and the ability to understand speech in noise. I will also describe how this photonic technology can be leveraged to build improved cochlear implants and other implantable hearing devices. Next, I will discuss progress made toward understanding a basic scientific question: Why do mammals have three flexible middle-ear bones whose mass is concentrated away from the entry axis to the inner ear, whereas non-mammals have just a direct connection from the eardrum to the inner ear via a columella? There are multiple factors that have likely led to the development of the mammalian middle ear, including improved high-frequency hearing via the air-conduction hearing pathway, reduced perception of self-generated sounds via the bone-conduction hearing pathway, and protection against high input levels. We use µCT imaging, 3D vibration measurements, and finite-element computational models to address this fundamental question. Finally, I will describe an imaging and modeling project that aims to reveal how the thousands of piezoelectric-like outer hair cells within the organ of Corti of the inner ear manage to support the high sensitivity, high frequency selectivity, and wide bandwidth of hearing in mammals. To this end, a “feed-forward/feed-backward” hypothesis for cochlear amplification is being tested using finite-element and asymptotic computational models of the mouse cochlea, which will be improved using 3D morphometric parameters obtained from two-photon in situ imaging of genetically altered mice with fluorescent proteins expressed in their cell membranes.

Sunil Puria received his Bachelor’s degree from the City College of New York, his Master’s degree from Columbia University, and his Ph.D. from the City University of New York, all in Electrical Engineering, with most of his Ph.D. research taking place at AT&T Bell Labs in Murray Hill, NJ. He went on to do a Postdoctoral Fellowship at MIT, and was an Adjunct Faculty Member at Harvard University Medical School. Currently, Sunil holds dual positions at Stanford University as an Associate Professor (Consulting) in the Departments of Mechanical Engineering and Otolaryngology, and as the Chief Scientist at EarLens Corporation. He has published over 50 papers in peer-reviewed journals, holds over 20 US and 5 international issued patents, has over 40 patents pending internationally, and has co-edited a book. Sunil served on the editorial board for the Journal of the Association for Research in Otolaryngology (JARO), served on the NIH AUD study section for the National Institute on Deafness and Other Communication Disorders (NIDCD) until 2014, and is a fellow of the Acoustical Society of America.