You probably never knew who was responsible for creating the infectious refrain, but Toots Thielemans' sound is burned into your brain. It likely happened before you were old enough to even pronounce "chromatic harmonica," the instrument on which he recorded the opening choruses of the Sesame Street theme. While hardly representative of a 60-year career spent creating some of jazz's most hauntingly beautiful improvisations, his association with the quintessential children's program is somehow fitting.

Despite collaborating with masters such as Benny Goodman, Charlie Parker, Ella Fitzgerald, Dinah Washington and George Shearing, it's easier to picture the diminutive 86-year-old Belgian-born musician as a regular on Sesame Street than on New York's 52nd Street. It's not just his round face and white hair, his gentle charm and his soft accent. Nor the childish sobriquet he was tagged with as a young man on the Belgian jazz scene because, he says, his given name Jean Baptiste "just didn't swing."

Mostly it's his emotional openness, sensitivity and guileless nature that seem to make him so well suited for dealing with children. These attributes also shape every note he plays. "That's what you call maturity, when all of your experiences, all your joys and pains blend together in the way you blow an instrument or the way you touch a guitar," says Thielemans, who performs as a special guest with pianist Kenny Werner's trio at Kuumbwa on Monday.

While the harmonica is a staple of the blues world, Thielemans' chromatic harmonica is an entirely different instrument, capable of the most sophisticated harmonic progressions. He's also a fine jazz guitarist and astounding whistler, skills he put to use on the international 1962 hit recording of his tune "Bluesette," which he still regularly employs as a finale.

No musician has been more closely associated with Thielemans over the past decade than Werner. One of jazz's most respected pianists, Werner's book Effortless Mastery: Liberating the Master Musician Within has influenced countless players.

Werner presents Thielemans as a special guest on a series of California gigs with his stellar trio featuring veteran bassist Scott Colley and the extraordinary Mexico City-born drummer Antonio Sanchez (whose performance with his band Migration was a highlight of the last Monterey Jazz Festival).

"The language we deal in is seriously beautiful harmony and melody," Werner said. "So one might be tempted because it's melodic to call it traditional. I don't think it is. I've had musicians I really respect listen to us play and flip out. The music is highly interactive and it has that dangerous edge to it too."

KENNY WERNER TRIO WITH TOOTS THIELEMANS Monday, Nov. 17, 7 and 9pm at Kuumbwa, 320-2 Cedar St., Santa Cruz. Tickets $25 advance/$28 door; 831.427.2227 or www.kuumbwajazz.org

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