Microphone array beamforming with near-field correlated sources.

Abstract

As the price of omnidirectional microphone arrays has fallen, new applications have emerged for large room audio capture. Further, large room acoustics use loudspeakers, which create correlated sources and severely limit the use of optimum beamformers. Most sources are in the near field due to the large wavelength of speech. Widrow and Kailath’s work on correlation in sonar and radar assumed far field, but it cannot be directly applied to near-field acoustics. A new beamforming method has been devel-oped, which incorporates near field and correlation. The source bearings are estimated and an uncorrelated model is formed. A better DOA estimator was developed for the near-field correlated case limited by the width of the mainlobe. The new beamformer is able to null strong, perfectly and nearly perfectly correlated signals using the uncorrelated model and minimum variance distortionless response beamforming.