Cochlear Analog Transducers

Professor Karl Grosh,
Associate Professor of Mechanical Engineering,
Associate Professor of Biomedical Engineering,
University of Michigan

ABSTRACT:
The cochlea is a marvel of micromechanical engineering. This tiny organ is responsible for performing real-time, time-frequency analysis. In the mammalian cochlea, frequency analysis is achieved by means of hydromechanical coupling of a variable-width structural membrane with a water-like ionic fluid. Three thousand spatially distributed cells sense shear motion of the fluid while active force-generating cells boost low level sounds for enhanced gain. Our group has been using microfabrication techniques to construct a microphone that emulates the cochlear design. This cochlear analog transducer (CAT) separates the frequencies of sound spatially, using the properties of coupled structural acoustic wave, just as in the biological cochlea. We report on our efforts at microfabrication of the passive device, utilization multi-channel capacitive and piezoelectric sensing modalities, and progress on developing local active control laws for enhancing the filtering of the device.

BIO:
Karl Grosh received his BS and MS degrees in Engineering Science from The Pennsylvania State University in 1985 and 1988, respectively. After working as a Research Scientist at the Naval Research Lab in Washington DC from 1987-1990, he attended Stanford University from 1990-1994, receiving his PhD in Mechanical Engineering. Since 1994, he has been a faculty member at the University of Michigan where he holds the rank of Associate Professor of Mechanical Engineering with a courtesy appointment in the Biomedical Engineering Department. Professor Grosh won the NSF Career Award (1999) and the Office of Naval Research Young Investigator Award (1999). His current research interests are in cochlear mechanics, the biomechanics of growth, and the design and fabrication of electroacoustic transducers.