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for Computational Models for Cochlear Mechanics
Computational Models for Cochlear Mechanics 

Normal hearing relies on the carefully orchestrated, coupled response of the mechanical, electrical, and acoustical (fluidic) domains of the cochlea. The fluctuating electrical response is a manifestation of a subtle feedback control scheme coded into the mechanics of the cochlear structures; this electromechanical control is necessary to provide the fine frequency discrimination and nonlinearity seen in normal cochlear responses and neural data. In our work, we are particularly interested in assessing the role of the mediator of this active control, the outer hair cells.  We will show a physiological model of the cochlea that enables analysis of in vivo experimental results and the development of hypotheses of cochlear function. 
Cochlear mechanics seems an innocent computational problem.  Incoming airborne acoustic energy drives a small, snail-shaped organ filled with a water-like fluid inducing nanometer scale displacement.  However, even though the displacements are on the order of a nanometer, the response is nonlinear, the wavelengths of interest on the order of a 200m, and the structures are small.  These factors conspire to make direct numerical simulation untenable. In order to make progress in physiological modeling, hybrid numerical approaches are used.  In this talk, we will present approximate methods that enable the inclusion of viscous microfluidic effects in a computational framework.  In particular, a variational approach amenable to inclusion in a finite element based code will be presented.  Results for this method, which retains the accuracy of a Navier-Stokes formulation with the computational cost of a standard scalar acoustic formulation, will be given along with the limitations of the method.
Short Bio:
Karl Grosh received his B.S. and M.S. degrees in Engineering Science from The Pennsylvania State University. After working as a Research Scientist at the Naval Research Lab in Washington DC, he attended Stanford University receiving his PhD in Mechanical Engineering. Since 1994 Karl has been a faculty member at the University of Michigan, where he is now a Professor of Mechanical Engineering and Biomedical Engineering.  In 2009 he co-founded Baker-Calling, Inc. to commercialize piezoelectric MEMS microphones.  Karl is a Fellow of ASME and the Acoustical Society of America.  His current research interests include cochlear mechanics and the design and fabrication of electroacoustic transducers including the fabrication of an artificial cochlea.
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