This paper presents the design and evaluation of a microphone array. The proposed evaluation index is the directional characteristic of delay and sum beamforming, which is used to optimize the microphone array design. Using beamforming simulation, a microphone arrangement that minimizes sidelobes and improves the basic performance of beamforming is selected. The new hardware has omni-directional directivity and high tolerance for exogenous noise. It has 32 microphones on a 335-mm diameter disk designed to be mounted on a mobile robot. The microphone array performance is verified in different real environments. Experimental results in indoor/outdoor sound localization show the effectiveness of the array in reverberant environments and its robustness against different pressure sound sources for covering larger areas.