Jason Serinus, limbering up as he paces his living room, is dressed for work: 1930s wool tuxedo; second-hand white Brooks Brother shirt; mother-of-pearl studs; black silk bowtie, golden cuff links, gleaming black Corfam shoes.

In a moment, he will commence to whistle.

He will whistle, in the key of B flat, the aria "Voi Che Sapete," from "The Marriage of Figaro," by Wolfgang Amadeus Mozart.

It is a pained, tremulous and delicate aria, an aria that begs introduction.

Serinus obliges: "Cherubino is a young boy just entering adolescence, and he 's very confused about what's happening to him. . . so in this aria he tries to make sense out of everything by, in perfect balance, asking the question, "What is love?"

Serinus turns on the cassette recorder. He drinks some purified water from a mug. The flut solo floats up into the living room and Serinus gazes toward the ceiling, swelling through the shoulders and clasping his hands, prayer fashion, before him. He suck in a soft stream of air, purses his lips into a plump peach rosette, and whistles.

And whistels .

Forte , he whistles a searing vibrato. He whistles a fragile scrap of a dirge. His cheeks throb. His lips quiver. hHis palms turn up, supplicating. The white pleats of his tuxedo shirt rise and fall like a bellows. He gulps air and closes his eyes and whistles the aria into its hushed finale. Then he opens his eyes, annoyed by the distraction of a camera, and says somewhat unnecesarily, "I'm a phenomenon."

Jason Serinus, a 34-year old black-haired Master of Postural Integration whose Long Island bar mitzva picture sits in the living room next to his collapsible microphone stand, is a professional soprano whistler. "Elevating whistling from the level of novelty to that of a valid, moving aritistic medium," reads his resume.

You may hear him, this very evening, if you turn on your television set and watch "She's a Good Skate, Charlie Brown" (Channel 9 at 8 p.m.). Serinus whistles the part of Woodstock, the melodious bird. His operatic number for the evening is Puccini's "O Mio Babino Caro."

His whistling has been described by various Bay Area music critics as "virtuosic," "a magicall gift," "a high melodic waterfall," "disembodied," "amazing," and "other-worldl." One critic, in a fit of semantic excess, described Serinus as sounding "less like a mere mortal than some exotic bird of and in paradise." He has performed with the Diablo Valley Symphony, where he whistled La Palone and Micnela's Air from Carmen, with the Oakland Symphony Octet, where he whistled various airs from Puccini, Schubert and Strauss; and twice as an Opera Fair soloist in San Francisco's Wiar Memorial Opera House.

"People expect me to be able to do variations from "Dixie,'" Serinus says disdainfully sitting on a wooden chair in his living room while he drinks more purified water. "That's not what I do. When I started performing, I had never heard of a recording of another whistler. I knew of no prescedent for what I did. Most whistlers, they grew up in the country or something, they whistleld to birds when they were six years old."

Serinus begins eating a banana. "I started whistling to Caruso. And Lotte Lehman" (the German soprano, who died in 1976). "And Schwarzkopf" (Elisabeth Schwarzkopf, also a German soprano). He also feels a special debt to Leontyne Price, although he has never met her, and would some day like to didicate to Price in performance, Puccini's Cazone di Doretta, from La Rondine. "The ultimate statement of romantic love," Serinus says. "I learned it from Price, and it's basically Price's territory."

He is slender, dark eyed, and dark eyebrowed, with the kind of sculpted good looks that smack you in the face when he walks into the room. He exudes theatre: the tragic wistfulness that besets him through Puccini the wide-eyed muggin when he launches into Irving Berlin and Cole Porter. During one of his energetic performances of "It's Only a Paper Moon," Serinus may sprain his eyebrows.

There was a time, back in the days he does not speak much about, when Serinus was not Serinus. He had another name, which he does not make public. He made his living as a practitioner of Postural Integration, which he describes as a technique for releasing the body's connective tissue. He was himself posturally integrated -- indeed, he had realigned his own gums so well that his whistle opened up in altogether new ways -- and he was dining one night with a friend of his who owned a pet store and therefore kept numerous birds loose in her house.

Serinus - who - was - not - then Serinus began to whistle, and these birds he says, "went crazy." A parakeet landed on his shoulder. A quail sat at his feet. "They're in love with you," said the pet store owner. "You should have a bird name."

So he got one. "Jason Serinus is this wonderful, flowing, musical name," he says. "It's the genus of songbirds (serinus) of which the canary is a member."

He presented his first performance on a Berkeley FM Radio station in 1973. "Pieces I had no right whistling at that point," he says. "My pitch was atrocious. So was my breathing. So was my vibrato."

Serinus had heart, and ambition, and pliant lips. Serinus had a passion for music: he thought Schubert's songs had God in them, and Mozart was wonderful, and Puccini was splendid. But Serinus had no coach. He stumbled along on his own, whistling concerts at a local bar, until finally he found a teacher -- "a wonderful bright women of golden light."

She honed his pitch. She tightened his vibrato. He learned to relalx his jaw, relax the back of his throat, control his diaphragm, keep his mouth from drying out mid-aria.

"That's how I've gotten this extraordinary range," he says.

Phone call. "This is Jason." Pause. "No, no, it's Jason. Pause. His voice gets testy. "Okay -- I'm a virtuoso whistler! ! !"

Serinus hangs up and simpers, mimicking the newsman on the other end of the line. "What is it exactly that you do?' He rolls his eyes: "He thinks I'm a novelty act. Maybe I spit wooden nickels, and whistle standing on my head, popping soda crackers."

This is, of course, an occupational hazard. "I'm too much of a curiosity and I'm too much of a character," Serinus says. "The main thing is, I want people to hear me."

And then?

"Shows can be written about me. A series can be written about me. Often people look at me and say, 'You're right out of Noel Coward.'"

Carnegie Hall?

"I mean, why not? If it's musically valid it belongs there."