Continuous scan (CS) beamforming is a novel approach that can improve the dynamic range of a microphone array used for source localization. In the conventional beamforming approach in which spatially fixed sensors are used, the number of sensors employed determines the dynamic range of the array. Whereas, in the CS approach, by employing moving sensors in a prescribed motion, the effective number of sensors (so-called virtual sensors) used for beamforming can be greatly increased and, therefore, it can provide enhanced dynamic ranges close to the theoretical limit. In the CS process, for reconstruction of the time data acquired by moving sensors, stationary microphones are used for phase referencing. At ATA Engineering Inc., (ATA) a rotating, planar configuration array of sixty microphones was designed, built, and tested in a soundproof chamber with spatially distributed acoustic sources inside. Results of two CS-based methods (with and without the use of reference sensors) showed that the array can achieve a much better localization performance, without increasing sensor budgets, than the fixed-sensor-based conventional beamforming. CS beamforming is able to discriminate tested sources that are almost 18 dB apart. With the enhanced dynamic range, CS will be particularly useful in localizing secondary noise sources not only in an idealized, soundproof acoustic environment but also in a complex, factory-noise environment with high-level background.
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