Blind rhythmic source separation: Nonnegativity and repeatability

An unsupervised method is proposed aiming at extracting rhythmic sources from commercial polyphonic music whose number of channels is limited to one. Commercial music signals are not usually provided with more than two channels while they often contain multiple instruments including singing voice. Therefore, instead of using conventional ways, such as modeling mixing environments or statistical characteristics, we should introduce other source-specific characteristics for separating or extracting the sources. In this paper, we concentrate on extracting rhythmic sources from the mixture with the other harmonic sources. An extension of nonnegative matrix factorization (NMF) is used to analyze multiple relationships between spectral and temporal properties in the given input matrices. Moreover, temporal repeatability of the rhythmic sound sources is implicated as common rhythmic property among segments of an input mixture signal. The proposed method shows acceptable, but not superior separation quality to the referred drum source separation systems. However, it has better applicability due to its blind manner in separation.