Vocals can sometimes be removed from an audio track with a digital audio editor. Here I describe how to do it with Audacity, my preferred editor.
To remove vocals from a track, if vocals are in both left and right channels equally, open the file in Audacity. Click the name of the track, and in the drop-down menu that appears, select “Split Stereo Track.” Now you’ll have two tracks. Select one of them (doesn’t matter which) and go to Effect – Invert. Then click the name of the left (first) channel and go to “Make Stereo Track.” Finally, go to Tracks – Stereo to Mono. Save your project (don’t just export the file). At this point any action will segfault audacity-1.3.4, which is why you saved the project. Reopen audacity and open the project. Listen to check your work.
This will fail with considerable distortion if vocals are not equal in both left and right tracks.
There is a Nyquist plug-in called Center Pan Remover which automates the steps above. It also has an option to set a slider to “0 (band)” then choose specified frequencies to remove, instead of inverting the whole of one channel. This may be less destructive of the non-vocal parts of the music.
To install this plug-in, place “centerpanremover.ny” in the Plug-Ins folder inside the Audacity installation folder, /usr/share/audacity/plug-ins/. After restarting Audacity, select the track or audio you wish to remove the center-panned elements from and click Effect – Center Pan Remover… (it will be underneath the divider in the Effect Menu).
Note that although two channels of output are produced, the result is mono because both channels will be panned to center.