"DID YOU EVER HEAR the story about how Louis Armstrong got discovered in Chicago?" jazz trumpeter Lester Bowie asks with a knowing wink. "King Oliver heard Louis as he passed by in the street. When I started playing trumpet I would practice with my horn pointed out the window in the hope that Louis might drive by." Lester smiled like and old pro as he works up for his punch line: "Louis never heard me, but the neighbors sure did!"

Bowie's devotion to music comes naturally, Born in St. Louis to a long line of brass players, and oldest of the school bandmaster's three musical sons, Bowie learned early the wonders of his beloved trumpet. He also learned well. At 15 he was a union professional, although he had been earning money for gigs long before that. By 20, Bowie knew that music was his passion and his meal ticket.

Lester Bowie is visiting Harvard this week as the Kayden Artist-in-Residence, presented by the Learning From Performers Program. He will conduct his final improvisational workshop this afternoon from 4-6 p.m. in Cabot Hall Living Room, South House, 100 Walker St. The session is free and open to the public, and as the posters state, "Experience [is] Preferred...But Not Essential."

Teaching a group of musical-minded students Wednesday, Bowie exhibited all the color of a spirited orchestra conductor. "Loud!" he shouted, waving his cane in the air. "Play that stuff as loud as you were never allowed to as a kid!"

Bowie sauntered confidently through the young musicians, making everyone comfortable with his enthusiastic charm.

"One of the best ways I've found to help one to develop," he advised Wednesday night, "is to concentrate on something simple. It might turn out to be harder than you think." Bowie waved his cane again and said. "All right, now let's have some B-flat blues."

Called the "prince of post-modernist trumbet-with-a-punch" in a recent Down Beat article, Bowie began his rise to jazz stardom in the early sixties, working with "doo-wop" bands, and backing the likes of Albert King and Joe Tex. He moved to Chicago in the mid-'60s, became a part of the "Association for the Advancement of Creative Musicians," and in 1965 the critically acclaimed "Art Ensemble of Chicago."

"The Art Ensemble went to Europe in '69," Bowie recalls. "The cats really dug us over there, and we stayed for two years." The group caught on this side of the Atlantic when they returned.

The AEC, comprised of Joseph Jarman, Roscoe Mitchell, Famoudou Don Moye, and Malachi Favors Meghostut, abide by the motto "Ancient to the Future." As Bowie explains; "We want the different elements of music--some of our stuff has lovely little melodies, and a lot is wild stuff."

The AEC has won critical raves for its engaging and daring concerts, but Bowie remembers one particularly crazy event from their first European tour.

"We were doing this whole parody of rock concerts. Joseph [Jarman] came out naked as a joke, pretending to jam on a guitar, and everything was cool. We had these smoke bombs, though, and we were throwing em out into the audience--but then we found out they were fire bombs instead. Sleeping bags were catching fire and the crowd throwing the bombs back. People thought we were trying to sabotage the festival," he laughs.

BOWIE HIMSELF did more than 300 concerts in 1983 alone. Aside from the AEC, he travelled with Roots to the Source, a band made up of his ex-wife Fontella Bass, her gospel singing mother Martha, and brother David Peaston, along with drummer Philip Wilson (an old pal), and Chicago based saxophonist Ari Brown. Bowie also formed the new Brass Fantasy group from the core of the New York Hot Trumpet Repertory Company, and he plans to record with them at the end of this summer.

"One thing I'd really like to do is put together a 100-piece band and tour the world with them in 1986." Bowie laughs. "The possibilities are just unbelievable--you can send guys behind the audience and drive them crazy!"

No doubt Bowie will pull it off; in 1979, he led and conducted the "Sho-Nuff" 59-piece orchestra in New York City, and received, in his words, "a really wild response."

Bowie has recorded more than 50 albums--nine as a leader--and his sales have been steady, if never overwhelming. The AEC and Bowie have always been enormously popular in Cambridge.