Most saxophonists play their instruments standing up, but today, Prasant Radhakrishnan is sitting down. His legs are crossed, his back is upright; the saxophone droops like a brass pipe from his mouth to the floor.

The 25-year-old is seated on a rug in the one-room Sangati Center in the Mission District of San Francisco. Several dozen spectators, all of whom have removed their shoes at the door, wait for Radhakrishnan to begin. Finally he drops his head, closes his eyes and leans his left shoulder in to coax the first noise from the sax. It is, when it emerges, not a jazzy or bluesy sound but a soft, distinctly carnatic murmur that ascends briefly, then tumbles down deep like a drone.

Radhakrishnan, who lives in Oakland, plays South Indian classical, or carnatic, music like this around the world. He has performed in India, Japan, Canada, Barbados and across the United States. Three weeks ago, he did a sweep of colleges in western Michigan and Chicago. In a few months he'll be touring India. The young saxophonist is often accompanied by a carnatic drummer, or mridungam player, and a carnatic violinist, as was the case at the Sangati Center. Other times he plays with larger ensembles or with musicians independent of the carnatic tradition.

Tonight, when he takes the stage at the Climate Theater, he'll play with his jazz trio, VidyA.

"Prasant is redefining the way to play saxophone, and the way for us to listen to it," says Howard Wiley, an accomplished saxophonist and a regular at Yoshi's jazz club in Oakland. "He's coming from a very different place than I am, but his love for organic music, and his commitment to excellence, and just his attempt to master his instrument - those are the truest judgment of a musician."

Radhakrishnan's technique on the saxophone is unique. South Indian classical music is built upon ragas, seemingly simple lines of notes that, unlike scales in the Western tradition, have countless oscillations coloring each phrase. A stringed instrument like the violin or a wind instrument like the bamboo flute can reach these liminal tones to great effect. Conventional wisdom has it that the saxophone - a keyed instrument that emits audible gaps between each note - can't do the same. Indeed, the sax is almost never included in traditional carnatic ensembles.

But Radhakrishnan has developed novel fingerings and new reed techniques so that it can. He sits rather than stands, and throttles his chest and throat as though he were singing through the mouthpiece of the instrument.

"I focus a lot on the vocal aspect of the music," Radhakrishnan says. "In carnatic music, whatever you do, you try to mimic the vocal. Whether it be violin or flute or guitar, you're trying to make the instrument sing, literally to the point of matching words. The tone of the saxophone closely resembles the human voice, so while it may be challenging to play in the carnatic tradition, it really adds a new depth to the music."

Radhakrishnan is not the first to play saxophone this way. His guru, Kadri Gopalnath, is. The two met when Radhakrishnan was a 13-year-old living in Phoenix, and playing saxophone in a mediocre middle school band. Gopalnath saw talent in his future pupil and invited him to spend a summer studying at his home in southern India. Radhakrishnan, who at the time admits to being "bored by Indian classical music" but "intrigued" by his guru, agreed.

He soon began a gurukulam, or complete immersion, with Gopalnath. He slept on a bare cot behind his teacher's house. He took cold showers. Gopalnath awoke him most mornings before dawn and passed along knowledge of carnatic saxophone at any and every hour of the day.

"That first summer was one of the most memorable experiences of my life," Radhakrishnan says. "It was like reading 'Zen and (Confucius in) the Art of Swordsmanship' or something."

Radhakrishnan returned to India the next two summers. By 17 he had recorded his own solo album, "Swara Sudha." He attended the University of Southern California, where he earned degrees in international relations and music. He began to tinker with his own techniques and, as a musician who had grown up straddling two cultures (carnatic music and American jazz), mused over how to bridge the two.

Now three years out of school, Radhakrishnan has produced two more carnatic albums and spearheaded the Bay Area jazz ensemble, VidyA, that's pioneering trans-cultural terrain. David Ewell, who plays frequently with Wiley and Lavay Smith and has toured internationally with Lauryn Hill, is the trio's bass player; Sameer Gupta of the Supplicants and the Marc Cary Trio is on drums. Last year VidyA were resident artists at the Red Poppy Art House in the Mission District.

"When I listened to VidyA for the first time, it just seemed so clear that it was a very present-time music," says Todd Brown, a painter and co-director of the Red Poppy. "For Prasant, this is just what he hears when he goes to bed at night; it's literally an outgrowth of a person straddling two worlds. And it's giving artistic expression to that new ground, that new identity."

"Carnatic music is religious music," adds Ewell, who has had to work to integrate the bass into the sliding tones and polyrhythms of carnatic saxophone. "There's all sorts of layers of meanings to the ragas. That's true of jazz, too. Jazz and blues basically come out of the music of the black church, of gospels and spiritual songs. So there's a resonance there."

VidyA has recorded its first album, which is due out in April. Radhakrishnan will be playing with VidyA locally, and touring nationally with his carnatic saxophone until then.

"Ultimately, whatever tradition you're coming from, music has to touch you emotionally," Radhakrishnan says. "When I'm performing, I'm not trying to say, 'Here's some jazz,' or 'Here's a little splash of carnatic.' It's more organic than that. It's about making people feel on the most basic level."

Prasant Radhakrishnan

and VidyA will perform

at 9 tonight at the Climate Theater, 285 Ninth St. For ticket information, call (415) 263-0830.