Underdetermined Sound Source Separation Using Power Spectrum Density Estimated by Combination of Directivity Gain

A method for separating underdetermined sound sources based on a novel power spectral density (PSD) estimation is proposed. The method enables up to M(M-1)+1 sources to be separated when we use a microphone array of M sensors and a Wiener post-filter calculated by the estimated PSDs. The PSD of a beamformer´s output is modelled by a mixture of source PSDs multiplied by the beamformer´s directivity gain in the particular angle where each source is located. Based on this model, the PSD of each sound source is estimated from the PSD of multiple fixed beamformers´ outputs using the difference in the combination of directivity gains. Simulation results proved that the proposed method effectively separated up to M(M-1)+1 sound sources if the fixed beamformers were appropriately selected. Experiments were also conducted in a reverberant chamber to ensure the proposed method was also effective in practical use.