Beam Pattern Design and Performance Analyses for Circular Array with Spherical Baffles

The influence of a rigid spherical baffle on the response of a uniform circular microphone array (UCA) is analyzed and two eigen-beam beamforming arrays are designed in the eigen-beam subspace derived from the soundfield decomposition. Expressions of white noise gain (WNG) and directivity index (DI) are derived for the designed arrays. Performance analyses are carried out for the designed arrays and compared between those of the delay-and-sum beamforming array using UCA with and without a rigid sphere. Computer simulations demonstrate that the designed arrays have frequency-independent directivity with the cost of reduced robustness at low frequency band. The delay-and-sum beamforming array has constant WNG at all frequencies, while its directivity of which is reduced at low frequency band. The rigid sphere can improve the robustness for all the arrays.