Many people listen to recorded music as part of their everyday lives, e.g. from radio or TV programs, downloads or, increasingly, online streaming services. Sometimes we might want to remix the balance within the music, perhaps to suppress the vocals for entertainment purposes, such as karaoke, or maybe to learn how to play an instrument. All these applications could be possible only if we have access to separated sound channels (stems) for each musical audio object. In this project we dealt with source separation of polyphonic music while focusing on two audio channels: vocals and accompaniments.