‘Where is the Line’ is a track off Bjork’s 2004 album ‘Medulla’. The whole album is acapella, made up from various warped vocal tracks. Beatboxer Rahzel provides the beats and the Icelandic Vocal Orchestra provide the harmonies on this particular track. Its a pretty dark and intense tune, becoming almost completely disorientating by the end. Amazing. Check out the rest of the album, its one of her best.