Microphone Placement for Sparse 2D Beamforming Arrays

Presented in this paper is a method for determining the optimal microphone positions for a two-dimensional (2D) beamforming array, which will be referred to as the average-gain microphone placement (AMP) method. The AMP method is specifically intended for applications where an undesired sound (noise) is expected to come from a single direction and desired sound is expected to come from a range of directions. The optimum placement determined by the algorithm yields the best average performance over the range of anticipated directions of arrival, rather than the best performance in any single direction. The AMP method notably includes a procedure for reducing the performance characteristics of an array to a single-valued performance metric, which allows for a definitive optimum to be located. A typical application would be for filtering speech with a large noise source in a single direction, such as machinery or HVAC equipment. Both the optimization routine and the method for predicting performance can be applied to 2D microphone arrays of any size. Results that demonstrate the validity of both the optimization and performance predictive methods are shown and discussed.