Degenerate Unmixing Estimation Technique using the Constant Q Transform

The Degenerate Unmixing Estimation Technique (DUET) is a Blind Source Separation (BSS) algorithm for stereo audio. DUET depends on an amplitude-phase 2d histogram built from the differences between the two channels, where peaks in the histogram indicate sources in the mixture. If peaks overlap, separation becomes unfeasible. This is often the case for music mixtures. We propose to improve peak separation by building histograms from time-frequency representations based on the Constant Q Transform (CQT) instead of the Fourier Transform (FT). The CQT has a logarithmic frequency resolution matching the geometrically spaced notes of the Western music scale. We also adaptively resize histogram bins and use Wiener filtering to improve peak resolving and source reconstruction. Results on mixtures of harmonic musical instruments show improvement in separation, especially at low frequencies and for closely spaced sources.