A Perspective on Frequency-Domain Beamformers in Room Acoustics

Signals captured by a set of microphones in a speech communication system are mixtures of desired signals and noise. In this paper, a different perspective on frequency-domain beamformers in room acoustics is provided. Specifically, the observed noise signals are divided into coherent and incoherent signal components while no assumptions are being made regarding the number of coherent noise sources and the noise sound field. From this perspective, performance measures are defined and existing beamformers are deduced. In addition, a new and general tradeoff beamformer is proposed that enables a compromise between noise reduction and speech distortion on the one hand, and coherent noise versus incoherent noise reductions on the other hand. The presented performance evaluation shows how existing beamformers and the tradeoff beamformer perform in different scenarios.