AmbiSep: Joint Ambisonic-to-Ambisonic Speech Separation and Noise Reduction

Blind separation of the sounds in an Ambisonic sound scene is a challenging problem, especially when the spatial impression of these sounds needs to be preserved. In this work, we consider Ambisonic-to-Ambisonic separation of reverberant speech mixtures, optionally containing noise. A supervised learning approach is adopted utilizing a transformer-based deep neural network, denoted by AmbiSep. AmbiSep takes mutichannel Ambisonic signals as input and estimates separate multichannel Ambisonic signals for each speaker while preserving their spatial images including reverberation. The GPU memory requirement of AmbiSep during training increases with the number of Ambisonic channels. To overcome this issue, we propose different aggregation methods. The model is trained and evaluated for first-order and second-order Ambisonics using simulated speech mixtures. Experimental results show that the model performs well on clean and noisy reverberant speech mixtures, and also generalizes to mixtures generated with measured Ambisonic impulse responses.