In the high-C concert world known for its conceits, Lucy Shelton's humility is refreshing. "I don't have a particularly good voice," says the 37-year-old soprano. "I mean, I've learned to get the most out of it, but it's not an uncommonly special one." Yet no less seasoned a critic than Donal Henahan of the New York Times has asked, "If Miss Shelton is not headed for a major recital career, who in the world is?"

Shelton is already established as a reigning maverick—onstage and off—from whom connoisseurs have learned to relish the unexpected. Last year when she captured a first prize in the Walter W. Naumburg Competition for an unprecedented second time, it was a triumph of her versatility. The Naumburg is the equivalent for American classical musicians of a U.S. Open tennis championship, and only Shelton has won it in two categories—in 1977 as a vocalist in the Jubal Trio, and in 1980 as a soloist. "It was just a natural curiosity to see if I could go from a team to an individual art," she explains. "it's like wondering if Chris Evert Lloyd is going to win both the doubles and singles."

The habit of challenging herself has given Shelton a wide-ranging musical repertoire. Away from fancy-dress recitals, she has let her hair down as a backup vocalist for Judy Collins and the English folk-rock group Renaissance. "She's one of the most intelligent singers I know," says Naumburg administrator Lucy Rowan. "She can sing almost everything from Bach to Handel to Bernstein and Schwantner." Confides Shelton, "I look to sing the songs nobody even knows were written. I'm not afraid to explore the uncharted vocal ranges from the 12th to the 21st century."

A geologist's daughter and a direct descendant of the Mayflower Pilgrims John and Priscilla Alden, Lucy (her middle name is Alden) grew up in Claremont, Calif. in a family whose pastime was singing madrigals and Bach chorales. She and her music-making siblings (two sisters, two brothers) styled themselves the Gruesome Quintet. At age 3, she first studied piano; at 12 came the flute.

As athletic as she was artistic, she was a fearless backyard tree climber (though in 1961 her audacity caused her to fall 30 feet out of a tree and cost her two broken legs). By her mid-teens, Lucy decided that "music was more enjoyable than dating. To me, chamber music is a way of being in perfect harmony with somebody else." After Pomona College she went to the New England Conservatory, and voice became her ruling passion. In Boston she was befriended by Beverly Sills, who convinced her to strike out for New York and the musical big league.

For most singers of Shelton's caliber the ultimate goal is opera. But Shelton has studiously avoided auditioning for a company—not even for the New York City Opera, where Sills is artistic director. "I wouldn't want to take advantage of our personal rapport years ago," says Shelton. "Opera didn't pull me, although I think I could do it, and it may become appropriate to my career. In the meantime, I love what I'm doing." Her calendar for next season is already booked with some 50 concerts, among them her European debut in Paris next February.

Fiercely independent (her romance with a California sculptor broke up last year), Shelton and her cat, Chloe, share a mauve-painted loft apartment on Manhattan's Upper West Side. "Lucy has this East Coast streak of proper Boston manners, and at the same time this California offbeat flair," observes Hanson Fisher, who roomed with Shelton at college. "She drives a Jeep and wears clothes nobody else would dare to wear."

The acclaim that has come her way with her double Naumburg has hardly altered her funky style. Recalling her scuffling days of yore, she says, "I never bought furniture. I used doors for tables and boxes for chairs. I lived on cheese and yogurt, dried fruits and soybeans. You see, I had to weigh what was important," says Shelton, who chose to "submerge" herself in chamber music. "Somehow my priorities were always very clear."