Adding a rhythm section to A Capella tracks

Question

I have the task of setting up a beat (bass and drums) to already existing vocal-only tracks. (Male vocal, three-part harmony.) I've tried playing along, and while I like the feel of what I'm getting, I can't quite hit the sweet spot in terms of syncing to a rock-solid rhythm.

I'm fairly certain the song was recorded to a click track, but I don't have that audio data. Has anyone done this sort of thing successfully? How did you do it?

(This question straddles performance and audio, and is in part a test question. The situation is real, though.)

Answer 1

Many Digital Audio Workstation software packages will have beat detection features which can detect and map the beats of a track to a tempo sync track. If the a capella tracks were recorded with a click track, then you should see the detected beats mapped evenly throughout the song. Otherwise, you have the option to either adjust the tempo of the original recording, or to map the tempo of your rhythm tracks to follow the tempo variations.

Side note: Have you considered recording the bass and drums using human voices? Thumping your chest while singing the bass line can be pretty effective with some compression and a dash of tube sound.

Answer 2

Try writing a basic beat in a sequencer, where you can control the tempo. Play your sequenced drums up against the recording of the vocals only, and subtly vary the tempo until they line up.

The sequenced beat will be locked to a "click," so if you can get it to line up with the vocals, you now know the tempo of the vocals. You can set a metronome to this and then play to your heart's content.

This will only work if your vocals are indeed at a steady tempo.

I've done this using Ableton Live, not to an a capella track but rather to some recorded instrumentation, but the concept is the same.