Some of the audience reactions to a trio version of the Art Ensemble of Chicago at the Barbican were surprising in their shocked unfamiliarity with free music, a manner of making jazz now well over 40 years old. But they were understandable. Although this most theatrical and tradition-steeped of post-1960s free-improvising groups has often gone out of its way to extend a hand to unready audiences, here it uncompromisingly steered down a fierce improv path dominated by Roscoe Mitchell's whirling sax lines. It was a dazzling performance, but you needed to be ready.

This show was devoted to an Art Ensemble sound of old - the warm-toned, bluesy, eccentrically phrased trumpet of Lester Bowie, who died in 1999. The scalpel-sharp, acoustic Art Ensemble shared the programme with the thundering, electrified, drum'n'bass and soul-jazz ensemble Drum FM, led by UK-resident American drummer Marque Gilmore; both bands declared they had Bowie in mind for the night. Drum FM cornettist Graham Haynes even risked sporting Bowie's famous doctor's white coat, but since his own call-and-response playing was one of the most effective elements in the band's otherwise sprawling show, he got away with it.

Drummer Famoudou Don Moye rooted the Art Ensemble's performance with his ability to make the most abstract of time-patterns splash and swing. Bassist Malachi Favors - with his tribal face-paint looking more than ever like a benevolent old cat - was emphatic, if approximate in pitch on bowed parts. Roscoe Mitchell was plain breathtaking - and, in a series of alto and soprano excursions, he hardly took breath. He combined the type of jostling contrapuntal style favoured by the UK's Evan Parker with a jazzier rhythmic impetus and the slurred phrasing of the blues. The trio's all but psychic ability to collectively improvise slow, ambient meditations of absorbing vividness explored intensity levels rather than tunes, but proved that even after three decades together, no two Art Ensemble shows are ever the same.