Optimization and performance of broadband microphone arrays

This paper considers various wideband signal model optimization techniques and associated performance results for adaptive and steerable but fixed beam microphone array processing for hearing aid applications in freespace and reverberant conditions. We first review and compare various conventional broadband and narrowband array optimization techniques. These include the minimization of the output array power subject to desired signal distortion constraint; the maximization of the array gain subject to white noise gain and linear constraints; and maximum energy criterion subject to norm, linear, and quandratic distortion constraints. Then new results on maximum energy criterion broadband array optimization formulated for sub- band processing are presented. The uniformly spaced sub-band and the nonuniformly spaced sub-band using quandrature mirror filter approaches are treated. Finally, various simulation results under the maximum energy criterion for free-space and reverberant conditions are presented to demonstrate the usefulness of this class of microphone arrays.