Abstract
The superdirective beamformer, while attractive for processing broadband acoustic signals, often suffers from the problem of white noise amplification. So, its application requires well-designed acoustic arrays with sensors of extremely low self-noise level, which is difficult if not impossible to attain. In this paper, a new binaural superdirective beamformer is proposed, which is divided into two sub-beamformers. Based on studies and facts in psychoacoustics, these two filters are designed in such a way that they are orthogonal to each other to make the white noise components in the binaural beamforming outputs incoherent while maximizing the output interaural coherence of the diffuse noise, which is important for the brain to localize the sound source of interest. As a result, the signal of interest in the binaural superdirective beamformer’s outputs is in phase but the white noise components in the outputs are random phase, so the human auditory system can better separate the acoustic signal of interest from white noise by listening to the outputs of the proposed approach. Experimental results show that the derived binaural superdirective beamformer is superior to its conventional monaural counterpart.
Highlights
Microphone arrays combined with proper beamforming methods have been used in a wide range of applications, such as hearing aids, smart headphones, smart speakers, voice communication, automatic speech recognition (ASR), human–machine interfaces, etc., to extract signals of interest from noisy observations
We addressed the problem of superdirective beamforming with smallspacing microphone arrays
While it can achieve the maximum spatial gain to suppress acoustic noise, the traditional superdirective beamformer suffers from white noise amplification, which is serious at low frequencies
Summary
Microphone arrays combined with proper beamforming methods have been used in a wide range of applications, such as hearing aids, smart headphones, smart speakers, voice communication, automatic speech recognition (ASR), human–machine interfaces, etc., to extract signals of interest from noisy observations. The two sub-beamformers are designed to be orthogonal to each other so that the acoustic signal of interest in the binaural outputs is in phase while the (amplified) white noise is random phase This design is strongly motivated by studies and facts in psychoacoustics, which showed that the location (or direction) information of signals has a significant impact on speech intelligibility in the human auditory system. The proposed binaural heterophasic superdirective beamformer uses the IC magnitude information in a very different way where the two orthogonal sub-beamformers are designed to minimize the IC magnitude of the white noise components while maximizing the IC magnitude of the diffuse noise components in the binaural outputs to achieve better perceptual separation of the signal of interest and white noise.
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