A method for combining audio tracks, comprising: determining at least one music track that is musically compatible with a base music track; aligning the at least one music track and the base music track in time; separating the at least one music track into an accompaniment component and a vocal component; and adding the vocal component of the at least one music track to the base music track; wherein the determining includes determining a vertical musical compatibility between segments (122, 124) of the base track and the at least one music track based on a tempo compatibility, a harmonic compatibility, a loudness compatibility, vocal activity, and/or beat stability; characterized in that the tempo compatibility between the segment of the music track and the segment of the base track is determined by determining a tempo compatibility score which is higher the closer the tempo between the segments (122, 124) is; wherein the harmonic compatibility between the segment of the music track and the segment of the base track is determined by determining a harmonic compatibility score which is higher the closer the harmonic compatibility of the segments (122, 124) is; wherein the loudness compatibility between the segment of the music track and the segment of the base track is determined by determining a loudness compatibility score which is higher the closer the normalized loudness of the segments (122, 124) is; wherein the vocal activity is detected on the segment of the music track where a higher vocal activity in the segment results in a higher vocal activity score; wherein the beat stability is determined on the segment of the music track where a greater beat stability in the segment results in a higher beat stability score; wherein a vertical mashability score, on which a compatibility score of the vertical musical compatibility is based, is determined as the product of the scores of tempo compatibility, harmonic compatibility, loudness compatibility, vocal activity, and/or beat stability on which the vertical musical compatibility is based. determining at least one music track that is musically compatible with a base music track; aligning the at least one music track and the base music track in time; separating the at least one music track into an accompaniment component and a vocal component; and adding the vocal component of the at least one music track to the base music track; wherein the determining includes determining a vertical musical compatibility between segments (122, 124) of the base track and the at least one music track based on a tempo compatibility, a harmonic compatibility, a loudness compatibility, vocal activity, and/or beat stability; characterized in that the tempo compatibility between the segment of the music track and the segment of the base track is determined by determining a tempo compatibility score which is higher the closer the tempo between the segments (122, 124) is; wherein the harmonic compatibility between the segment of the music track and the segment of the base track is determined by determining a harmonic compatibility score which is higher the closer the harmonic compatibility of the segments (122, 124) is; wherein the loudness compatibility between the segment of the music track and the segment of the base track is determined by determining a loudness compatibility score which is higher the closer the normalized loudness of the segments (122, 124) is; wherein the vocal activity is detected on the segment of the music track where a higher vocal activity in the segment results in a higher vocal activity score; wherein the beat stability is determined on the segment of the music track where a greater beat stability in the segment results in a higher beat stability score; wherein a vertical mashability score, on which a compatibility score of the vertical musical compatibility is based, is determined as the product of the scores of tempo compatibility, harmonic compatibility, loudness compatibility, vocal activity, and/or beat stability on which the vertical musical compatibility is based.