Ghosts in Dreamland

On the Shadows and Light tour, Joni Mitchell did the voice-percussion duet with Don Alias, "Dreamland". To this day I suspect she had some kind of guide track as a cue to keep her on pitch. If you play an instrument, you'll notice she doesn't waver from a G natural. (In fact it also suggests the chord change: G-F-C-D-Emin)

Her sense of pitch is impeccable, or she had a cue. I don't think so. I always thought Jaco played on it and they muted his track. Ghosts.