Separation of harmonic sounds using multipitch analysis and iterative parameter estimation

A signal processing method for the separation of concurrent harmonic sounds is described. The method is based on a two-stage approach. First, a multipitch estimator is applied to find initial sound parameters which are reliable, but inaccurate and static. In a second stage, more accurate and time-varying sinusoidal parameters are estimated in an iterative procedure, which imposes certain constraints for the amplitudes and frequencies between the components of each sound. The proposed algorithm makes it possible to reconstruct separated sounds that are perceptually close to the original ones before mixing. Experimental data comprised sung vowels and 26 musical instruments. Sound separation was performed for random sound mixtures ranging from one to six simultaneous sounds. The system is able to produce meaningful results in all polyphonies, the quality of separated sounds gradually degrading along with the polyphony.