SDR (Signal-to-Distortion Ratio)

Signal-to-Distortion Ratio (SDR) is a widely used objective metric for evaluating the quality of audio source separation, expressed in decibels, where a higher score indicates a separated stem with less unwanted distortion and interference. It is the standard benchmark in separation research and competitions such as the Sony Music Demixing Challenge. (Note: in video, SDR instead refers to Standard Dynamic Range, an unrelated term.)