Time–Frequency Domain Spatial Audio Enhancement

Multi-microphone devices enable flexible recording of sound sources in the presence of interferers, noise, and reverberation. The most common signal enhancement techniques for microphone arrays are based on the design of directional filters or beamforming. This chapter provides a brief overview of these techniques, with a focus on post-filtering techniques. In adaptive beamformers there is a trade-off between directional selectivity and noise amplification which can be observed in the directivity factor. A class of adaptive beamformers are described as part of the informed spatial filters that combine beamforming with noise reduction. Time-frequency masking is commonly applied at the output of the beamformer to adjust the spectrum to better match that of the desired source signal. The post-filters are only capable of reducing uncorrelated or correlated noise in the beamforming output, and rely on the output of the beamformer for the suppression of the interference.

adaptive beamformers; multi-microphone devices; post-filtering techniques; signal enhancement techniques; spatial filters; time-frequency masking

• spatial audio
• speech