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Boundary Element Modeling of the Human Auditory System Timothy Walsh Sandia National Laboratories Albuquerque, NM Leszek Demkowicz, Richard Charles TICAM The University of Texas at Austin Austin,TX Motivation Schematic of the human auditory system Goals of Research • Compute Head-Related Transfer Function (HRTF) and compare w/ experimental data • Reproduce canal resonance modes • Goal-oriented adaptivity • A-patch C1 surface reconstruction • Parallelization of formation, solve, and error estimation Head-Related Transfer Function • HRTF maps pressure at eardrum vs frequency and angle of incidence • Useful for hearing aid design, virtual acoustical simulators, localization research • Individual signature • Benchmark for comparison Weak Form of Burton-Miller IE A-Patch Surface Reconstruction (Bajaj, Xu) A-Patch Surface Reconstruction Linear elements Quadratic elements Cubic elements Parallelization of BEM Goal-Oriented Adaptivity for BEM Goal-Oriented Adaptivity for BEM Goal-Oriented Adaptivity for BEM Goal-Oriented Adaptivity for BEM Goal-Oriented Adaptivity for BEM Goal-Oriented Adaptivity for BEM Goal-Oriented Adaptivity for BEM Goal-Oriented Adaptivity for BEM Goal-Oriented Adaptivity for BEM Goal-Oriented Adaptivity for BEM Goal-Oriented Adaptivity for BEM Goal-Oriented Adaptivity for BEM Goal-Oriented Adaptivity for BEM Goal-Oriented Adaptivity for BEM Goal-Oriented Adaptivity for BEM Goal-Oriented Adaptivity for BEM Areas of Interest for Scattering on Sphere / Half Sphere Mesh Adaptivity for Scattering on the Sphere Error in Quantity of Interest for Scattering on the Sphere Area of Interest for Scattering on Human Head Goal-Oriented Adaptivity on Ear L2 Residual Adaptivity Goal-Oriented Adaptivity Pressure Distributions on the Head at 500 Hz Pressure Distributions on the Head at 500 Hz Comparison with Experimental Data Comparison with Experimental Data Comparison with Experimental Data Comparison with Experimental Data Comparison of Response with and without Canal Comparison of Response with and without Canal Comparison of Response with and without Canal Comparison with and without Canal Comparison of Head and Sphere Resonance Mode of the Concha Resonance of Ear Canal Conclusions • BEM simulations can reproduce acoustical field outside and inside ear canal • BEM simulations can be used to generate clinical auditory data • BEM can reproduce resonance patterns inside ear canal • Goal-oriented adaptivity applied to BEM allows for high-frequency simulations without uniformly fine meshes Conclusions • Spatial cues not influenced by ear canal Future Work • Proposal for hearing aid simulations • Fast-multipole methods + adaptivity • Middle, inner ear simulations Acknowledgements • Richard Charles, initiation of project, ear canal mesh, etc. • NPACI: financial support (PI: J.T. Oden) • Dr. Bajaj, Xu, Center for Computational Visualization – Apatch procedure • Dr. R.A. van de Geijn: PLAPACK