Experimenting with the tutorial on “How to Remove Vocals from Songs with Audacity” http://audacity.wonderhowto.com/how-to/remove-vocals-from-songs-using-audacity-162272/ Import a track, then use Spit Stereo Track to Mono. In one track, use Effects-> Invert. It’s not perfect, but dropped in a project as a background track, it might work. The original song by some English band who’s career never took off 😉