Improving beamforming by optimization of acoustic array microphone positions

Abstract

Assigning proper positions to microphones within arrays is essential in order to reduce or eliminate side- and grating lobes in 2D beamform images. In this paper an objective function is derived providing a measure for the presence of artificial sources. Using the global optimization method Differential Evolution an optimized microphone configuration is obtained by minimization of this objective function. Results show that optimizing the microphone locations can significantly enhance the array performance. In a large part of the scan region surrounding the true source location, no side- or grating lobes are present, meaning that the source can be unambiguously located. From the optimization it is also found that the optimized array configuration shows the microphones distributed at almost constant distance. A linear relation is found which shows that the distance decreases with increasing frequency. This knowledge is important information for the design of an optimal microphone configuration.