The uninitiated were astonished and the cognoscenti reconfirmed Thursday night at the Bayou as the Art Ensemble of Chicago, in a single piece lasting 75 minutes, presented an impressionistic summary of black American music.

With some of its members in African dress and their faces bedecked with paint, the ensemble began in silent prayer, facing the east. Melodicon, shell, whistle, gourds and trumpet provided an intro followed by a fierce monologue of hoarse growls and strident falsetto by Joseph Jarman. "We ain't proposin' no answer - just askin' a question," was his coda.

Suddenly we were back in the 20s with a no-holds-barred polyphonic New Orleans stomp. One could hear Armstrong in Lester Bowie's trumpet and Bechet in Jarman's soprano saxophone; Mitchell's clarinet wove in and out contrapuntally and Malachi Favors slapped away at his bass while Famoudou Don Moye kept up a driving four/four.

Segments such as this (another took us back to the big band era, riffs and all) were interspersed with passages of all descriptions: Mitchell and Jarman played extended, sometimes unaccompanied solos that explored the entire range of the instruments, Bowie produced enormous trombone-like growls and squeezed-out shrieks, Favors and Moye played in different tempos.

Then all hell would break loose - Bowie cutting through the tremolos of the reeds with great foghorn blasts and rapid arpeggios in high register, bassist Favors shaking No. 10 tin cans, Moye propelling them all with ferocious intensity. Abruptly, Favors rushed to stage front, mallet and Chinese gong in hand, and with one resounding note ended the concert.

The Art Ensemble's music is chaotic, ecstatic and cumulative in its energy. It is irreverent, even outrageous, yet both a paean to the past and window to the future.