This paper presents a sound direction recognition system for intelligent mobile robots. We studied the analysis, design, and circuit realization of a standalone sound recognition system using multiple condenser microphones. Sound signals from three condenser microphones are integrated in a circuit to resolve the source direction. The minimum recognition angle of a triangular configuration is derived. A new decode method is proposed in this paper to resolve the sound direction. The proposed scheme uses a circuit to obtain direction information, an improvement to the conventional computer-based approaches. The recognition circuitry has been implemented using UMC 0.5/spl mu/m IC chip fabrication technology. Both simulation and practical experiments validate the desired performance. Experimental results show that the system recognizes sound direction with an accuracy of /spl plusmn/5/spl deg/. The sound recognition system has been integrated to a multi-robot system to investigate various robot control applications using whistle sound in a noisy environment. Experimental results demonstrate the effectiveness of the proposed method.