To shorten an output delay while a high sound source separation performance is ensured when a sound separation process based on an ICA method is performed. A second Fourier transform process execution cycle t2 for obtaining a second frequency-domain signal S1 used as an input signal of a filter process is set shorter than a first Fourier transform process execution cycle t1 for obtaining a first frequency-domain signal used for a learning computation of a separating matrix. When the time length of a second time-domain signal S1 is set shorter than a time length of a first time-domain signal S0, a second separating matrix used for a filter process is set by aggregating matrix components of a first separating matrix obtained through a learning calculation for every a plurality of groups.