A signal processing system includes a filter unit, a conversion unit, a decomposition unit, and an estimation unit. The filter unit applies, to a plurality of time series input signals, N filters estimated by independent component analysis of the input signals to output N output signals. The conversion unit converts the output signals into nonnegative signals each taking on a nonnegative value. The decomposition unit decomposes the nonnegative signals into a spatial basis that includes nonnegative three-dimensional elements, that is, K first elements, N second elements, and I third elements, a spectral basis matrix of I rows and L columns that includes L nonnegative spectral basis vectors expressed by I-dimensional column vectors, and a nonnegative L-dimensional activity vector. The estimation unit estimates sound source signals representing signals of the signal sources based on the output signals using the spatial basis, the spectral basis matrix, and the activity vector.