MUSIC : Sharing Her Feelings : Kevyn Lettau finds that expressing her emotions in song comes naturally.

It was a fluke that got Kevyn Lettau singing in public.

Lettau was 17 when a schoolmate who led a band heard her singing as she walked through a hallway at Torrey Pines High School in Del Mar. “He told me I had a really nice voice and asked me to join his group,” Lettau, now 33, recalled.

That incident was indeed serendipitous, for Lettau wasn’t planning on being a singer. She wanted to be a dancer. She had studied modern dance and had appeared a few times with a San Diego-based dance ensemble, Three’s Company.

But Lettau, whose name is pronounced Leh- toe, soon found out that singing, which she’d enjoyed all her life, gave her something that she wasn’t getting from her dancing: a means for self-expression that came to her naturally.

“I think I was better at singing, right off the bat. And it was a vehicle to express my joy, my pain and get an immediate response,” said Lettau, who will appear tonight and Saturday at Le Cafe in Sherman Oaks.

The importance of audience response was solidified when Lettau, as part of guitarist Peter Sprague’s Dance of the Universe three-piece orchestra, sang on a street corner in Del Mar each Sunday during her 18th summer.

“I could see that people enjoyed it, that I was giving them something, and they showed me their joy by smiling and moving, and being touched,” the singer said at the Van Nuys home she shares with her husband, drummer Michael Shapiro.

“That was tremendously rewarding. It gave my life a new validity,” she said.

That same aspect of social interplay with her audience is the focal point of Lettau’s performances now. “I try to be sure that people always walk away from my shows feeling something, whether it be excitement or happiness, or even sadness,” she said. “I want to shake them in their bones.”

Lettau has catholic tastes. In person and on her two albums--”Kevyn Lettau” on Nova Records and last year’s “Simple Life” on JVC Records--she offers a variety of material, from pop and R & B numbers to jazz-influenced takes of classic standards and Brazilian pieces.

She said she likes a broad scope because “that’s who I really am,” but finds, at least in terms of the marketplace, that she’s putting herself at a disadvantage by not being more specific stylistically.

“I feel like I’m stuck between a rock and a hard place,” Lettau said. “I don’t want to be pegged to be a certain kind of singer, but that’s the way the market is. Either you’re an R & B singer or a pop singer, or country. There doesn’t seem to be a category for ‘good’ singers.”

Lettau said that of all the styles she performs, it’s really Brazilian music that she’s in love with. Asked why, she answers by shooting questions right back.

“Why do some people like papayas or full moons? Why do some people like to read books? It was the kind of thing that when I heard Brazilian music when I was 13, that was it. I loved it. There was never a question.”

“Simple Life” has four tunes co-written by such Brazilian notables as Ivan Lins, Dori Caymmi and Kleber Jorge, and Lettau has been a part of Sergio Mendes’ band for eight years.

Owner Dale Jaffe of Le Cafe--where Lettau will be backed by Shapiro, pianist Bill Cantos, bassist James East and saxophonist Scott Mayo--is also a devoted Brazilian music buff. “Kevyn sings Brazilian songs better than any American I’ve ever heard,” he said. “She’s really studied the music, has got it down and interprets it wonderfully.”

Shapiro, who also performs with Mendes, said he and his wife have a solid working relationship. “We respect each other and connect really well musically,” he said. “And that’s fortunate because with husbands and wives who work together, it can be rough. But if you want one man’s opinion, this is really fun.”

Raised in the United States and Germany--her father is German, her mother American--Lettau moved to San Diego at the age of 15. Her primary musical training came from working in clubs in San Diego in her early 20s, and for a while she was accompanied by ace pianist Butch Lacy.

“He was working with Sarah Vaughan at the same time,” Lettau recalled. “He’d work weekends with her, and then come back and work with me. At first I was horrified and so nervous I’d almost throw up. Here he was working with one of my idols and then with me. But it was a tremendous learning experience, and I became a much more mature singer because of it.”

Where and When Location: Kevyn Lettau at the Room Upstairs at Le Cafe, 14633 Ventura Blvd., Sherman Oaks. Hours: 9 and 11 p.m. today and Saturday. Price: $10 cover, two-drink minimum. Call: (818) 986-2662.