Continuous Scan Beamforming Using a Rotating Microphone Array for Identification of Highly Varying Amplitude Acoustic Sources in a Soundproof Chamber

Continuous scan beamforming (CSBF) 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 CSBF 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 CSBF process, for reconstruction of the time data acquired by moving sensors, stationary microphones are used for phase referencing. At ATA Engineering Inc., a rotating, planar configuration array of sixty microphones was designed, built, and tested in a soundproof chamber with spatially distributed acoustic sources inside. Results showed that CSBF has a much better localization performance than the stationary-sensor-based conventional beamforming; CSBF is able to discriminate tested sources that are almost 18 dB apart. With the enhanced dynamic range, CSBF 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.