Voice Separation - A Local Optimization Approach

Voice separation, along with tempo detection and quantisation, is one of the basic problems of computer-based transcription of music. An adequate separation of notes into different voices is crucial for obtaining readable and usable scores from performances of polyphonic music recorded on keyboard (or other polyphonic) instruments; for improving quantisation results within a transcription system; and in the context of music retrieval systems that primarily support monophonic queries. In this paper we propose a new voice separation algorithm based on a stochastic local search method. Different from many previous approaches, our algorithm allows chords in the individual voices; its behaviour is controlled by a small number of intuitive and musically motivated parameters; and it is fast enough to allow interactive optimisation of the result by adjusting the parameters in real-time. We demonstrate that compared to existing approaches, our new algorithm generates better solutions for a number of typical voice separation problems. We also show how by changing its parameters it is possible to create score output suitable for different needs, , piano-style orchestral scores.