Singer Bobby McFerrin knows the mixed blessing of a hit song. His 1988 pop hit "Don't Worry, Be Happy" earned him sales that most jazz vocalists would kill for, but, somehow, people missed the irony. They also failed to realize that the full sound of the song came from his voice -- and his voice only -- by means of multi-tracking.

Since "Don't Worry," McFerrin has avoided not only the mainstream but words as well. Instead, he has focused on the most expressive -- and most ancient -- musical instrument around, the human voice.

To call McFerrin a singer would be to underestimate the range of sounds he commands. It would be better to say he performs on voice or "plays his vocal apparatus." After a performance in France, a researcher into ancient African languages asked McFerrin how he had managed to learn so many. He hadn't, he was only improvising. But somehow his intuitive approach led back to the sounds of those lost languages.