Early experimental results for a large-aperture microphone-array system

Microphone arrays offer a potential solution to the important problem of obtaining high-quality sound pick-up from remote acoustic sources. Most reported results for microphone array technology have been theoretical, proposed algorithms with predicted performance, or based on ideal or near-ideal simulations of microphone-array systems and room environments. Previous work that is based on real data has usually been for a small number of microphones. In this paper, for the first time, measured results for a large number of microphones, 256, in a large-aperture, real-time, all DSP system are reported. The array system is mounted in a moderate-sized (8M/spl times/8M) room with a significant reverberation time. While listeners to the locationing/tracking/beamforming system claim to hear near-close-talking microphone performance when the system acquires a talker, our measured results of the real-time system indicate that a true 9 dB separation of a source from other sources in the room has been achieved and that reverberant effects have been significantly reduced. This level of isolation is maintained at all locations throughout the room. In addition to reporting these early performance measures, this paper discusses the nuances of the real-time algorithms, the latency in such systems, and introduces some of the issues of making real-time, real-room measurements.