You’ve seen how to remove vocals to create karaoke tracks, but what if you don’t want the music? Using a similar process and good source audio, you can ditch the instruments and keep the vocals for an a cappella effect.
Isolating the vocals works like removing vocals; in both cases we combine the original waveform with an inverted waveform to “subtract” the part we don’t want. It will leave us, in this case, with the vocal track. In order for this to work, however, you need to have a studio version of the instrumental track. Removing the vocals to get an instrumental track and then trying to isolate the vocals does not work in this case. Don’t be disheartened if you don’t have one ready. Many studios release the instrumental tracks (with and without backup vocals) for use with things like karaoke. There are plenty of places online where you can buy these tracks, like Karaoke-Version.com, and some singles and records even have them on the B side, so all in all, it shouldn’t be too difficult to find them for most popular artists. These full-quality instrumentals usually really work well for isolating vocals.
As with center-channel (vocal) removing, the better the quality of the original tracks, the better the effect works. If you’re using MP3s, do whatever you can to avoid using tracks with a lot of clipping. This will ruin the effect over those parts. You can highlight where clipping occurs on your tracks in Audacity by going to View > Show Clipping.
As opposed to the final mono track you get from removing vocals, this method will leave you with a full stereo track. As such, it becomes more important to try and match the quality of both tracks before you isolate the vocals.
Open up Audacity and import both the regular and instrumental tracks.
Select the Time Shift Tool to roughly align the two properly. Next, zoom in really close, and then zoom in more. You want to see the wave function very closely.
Take the proper time to align this as closely as you can. pick a peak or trough in the left channel of one track and match it precisely with the left channel of the other track. If the alignment isn’t right, the process won’t really work.
Once you’ve got it as close to perfect as you can, click on the Selection Tool. Double click on the instrumental waveform to highlight all of just that one track, and go to Effect > Invert.
Next, hit Ctrl+A to select all of both tracks. Go to Tracks > Mix and Render.
You’ll get one combined track that should have a more diminished amplitude where the vocals were kept and the instrumentation removed.
Give it a listen. If there’s something off, just redo it. The toughest part is in the alignment, especially if both tracks are of very different lengths.
It’s really easy to isolate the center channel for your own projects. You can study the singer’s methods this way, or listen to just the guitar solo. And, with the internet at your disposal, you should have no trouble tracking down instrumental versions of songs you like for a reasonable cost or for free.