For the last 30 years, Bobby McFerrin could have contented himself with just being, as they say, "an act" and an unrivalled one at that. Possessed of a four-octave voice, lightning improv reflexes, and the ability to mimic everything from an opera bass to a Charlie Parker bop solo via the sound of a car shifting gear, he remains the master of the solo-voice show.
But an act he refuses to be, and even at a Barbican concert (backed by Pete Churchill's fine 28-piece London Vocal Project) hooked to his most ambitious-ever album, McFerrin still spent much of the gig jamming with his fellow performers and the audience. Inevitably, his skills invite a: "How the hell does he do that?" But he also reminds listeners that all humanity carries the same instrument as him and that music's roots are communal, which stardom has no business obscuring.
Typically he began seated, quietly singing a little uptilting falsetto melody while beating the groove on his chest. A deeper, soul-vocal line emerged (in McFerrin's private language, which sounds like English but isn't), then his trademark register-leaping skids, ending on a finger-snap. He then got the choir to sing a riff to the basses, playfully conducting its spontaneous overlaying all the way up to the sopranos, before unfurling his own improvised line over the top.