Wave-Domain Residual Echo Reduction Using Subspace Tracking

This article proposes a wave-domain residual echo reduction method for two-way immersive sound communication, which is based on wave field synthesis and uses uniform linear arrays of loudspeakers and microphones. This method is intended to improve the echo reduction performance in a mildly reverberant room with moderate increase in computational complexity. For improving such performance, this method takes residual echo due to reflected waves into account and uses a multi-tap echo-path model. To mitigate the increase in the method's computational complexity, it uses a size-reduced transfer function (TF) matrix instead of the full TF matrix. Specifically, this method extracts the dominant components of the loudspeaker signals adaptively by subspace tracking and estimates a size-reduced TF matrix that relates these dominant components to the residual echo. Simulation showed that the proposed method plus a wave-domain acoustic echo canceller (AEC) improved echo return loss enhancement by 10 dB compared to the conventional wave-domain echo reduction method plus the wave-domain AEC in a room with a reverberation time 180 ms. Its total computational complexity is twice that of the conventional echo reduction method plus a wave-domain AEC.