Traditionally, the goal of pop singers around the globe has been to make it big in America. It isn't simply that the United States boasts the biggest market for concerts and recordings, although that's certainly part of the appeal. It's rather that American music -- from Louis Armstrong to Michael Jackson -- has so permeated international pop taste that any singer who manages to conquer this country can truly be said to be sitting on top of the world.

But Milton Nascimento seems curiously unmoved by the prospect of becoming big in America. The 44-year-old singer, who will perform Sunday at the Carter Barron Amphitheater, has been a major star in Brazil since the late '60s, leading a pop explosion that definitively updated the samba sound of the '50s.

In part, Nascimento's approach was a reaction to the rock sound that was seeping into popular music everywhere, thanks to the likes of the Beatles and Motown. Mostly, though, it was Nascimento's distinctive roots that did the trick, for even when he paid tribute to the Beatles, in the song "Para Lennon e McCartney," he never let go of the jazzy sophistication of the Sa o Paulo sambas or the raw rhythm of his native province, Minas Geraes.

As a result, Nascimento maintains a special relationship with his fans in Brazil. He says he feels his fame is "a matter of great responsibility," insisting that he provides "a voice for those people who don't have the chance to express themselves."

That may explain why he never bothered to perform in this country until 1984, when he played two nights at Carnegie Hall -- small potatoes compared to the crowds of 150,000 or more he has drawn in Brazil.

Still, it isn't as if his fame has been constrained to the Southern Hemisphere. In the last 17 years he's recorded four albums for American labels -- three for A&M, and the recent "Encontros e Despedidas" for Polydor -- in addition to being featured on albums by Wayne Shorter, George Duke and Flora Purim.

Even though his American following has yet to grow beyond a cult audience, Nascimento enjoys a tremendous reputation among the cognoscenti. From critics such as Newsweek's Jim Miller and The New York Times' Robert Palmer to musicians like Shorter and Duke, Nascimento has received a steady stream of rave reviews. But he seems quite content to be liked for what he is, and rather than reshape his sound to suit American taste, as Julio Iglesias has done, Nascimento remains largely uninterested in what the U.S. market might fancy.

"I have never done a record for any market, not even Brazil," he says, speaking through an interpreter. "Even when I sang in English, it was not for the American market -- it was a consequence of my own life. I felt like doing that, so I did . . . If the new album happens to be a success in the U.S., fantastic. But that's not why I did it."

Nascimento deeply believes that "music is as life itself," and that's why he feels almost immune to commercial considerations. "I can't do otherwise," he says. "My music is my life, so that when I produce something, it's the result of something that I'm living. It's very far from the marketplace. If I see something in my work that's not correct, that doesn't reflect what I'm living, I won't release it. And I never allow anybody from the record company, or anywhere else, to interfere in my work."

The sentiments are admirable, but the full consequence of what Nascimento is saying doesn't sink in until the language problem is considered. Nascimento speaks Portuguese, as do most Brazilians, and, he says, "obviously, I prefer to sing in Portuguese, as it is my mother tongue." Still, he is "not disturbed by singing in English," stressing that it's more a matter of what is right for the songs. That's why his first three American albums featured some songs in English while the new one is entirely in Portuguese.

Still, it's not his words but his music that seems to most attract admirers. For instance, although Nascimento suggests that the reason American jazz musicians are attracted to his work is that "they are more open to all kinds of music," it's not hard to hear that the basis of his appeal lies with his melodies. Lean and expressive, his melodic ideas cut through chord changes with a minimum of effort, much in the same way a great jazz soloist might. Yet Nascimento plays down the jazz content of his songs. To him, his music "might have jazz in it, as it might have everything that occurs to me, from the music of Minas Geraes to no matter what."