Extension of virtual microphone technique to multiple real microphones and investigation of the impact of phase and amplitude interpolation on speech enhancement

A virtual microphone signal can artificially increase the number of channels of an observed signal, which leads to improved multi-channel speech enhancement performance. The conventional virtual microphone technique can only be applied to two real microphones, reducing its application to a limited range of situations. In this paper, we extend the virtual microphone technique to the interpolation of more than two real microphones. In the proposed method, the phase based on the plane wave model is linearly interpolated using an affine coefficients of the coordinates, and the amplitude is nonlinearly interpolated based on the β -divergence using coefficients inversely proportional to the distance between the virtual and real microphones. The experimental results shows that the proposed method is effective in improving speech enhancement performance. Furthermore, we investigate the impact of phase and amplitude interpolation on speech enhancement performance with two or three real microphones. The experimental results indicated that the benefits of phase interpolation based on plane wave model were limited, and that amplitude interpolation was important for improving speech enhancement performance.