POP MUSIC : The Voice Heard Round the World : Mercedes Sosa, a compelling figure in world music and a social activist, will make a rare L.A. appearance.

Mercedes Sosa, a charismatic advocate of freedom and justice often described as “the conscience of Latin America,” dominates a stage with the imposing presence of a primeval earth goddess.

Compactly built, dressed in a traditional red and black poncho, she vocalizes in a resonant contralto that moves easily from grand, declamatory cries to intimate whispers. Occasionally banging on a bombo laguero hand drum or clapping in rhythm, she becomes a populist icon.

“I sing,” says Sosa, “to the people who are suffering all over the world.”

And millions of those people have responded to her persuasive calls. The Argentine singer, one of the most compelling figures in world music, makes a rare Los Angeles appearance Thursday at the Veterans Wadsworth Theater.

But Sosa’s concerts--despite her great musical skills--are never about music alone.

“There are things that are more important than the vocal cords,” she explains in a phone interview from her home in Buenos Aires. “It’s what you feel when you make a sound, feelings of love, of solidarity with others. It’s not about technique. It’s about what is inside.”

What is inside, and what is outside as well.

Sosa has been a spokeswoman for society’s underclasses for more than three decades. She is articulate and soft-spoken. But the subject rarely strays far from the social and political topics that have become intrinsic to her thinking and her expression.

At 60, she has lost none of her power to arouse an audience, and shows no sign of relaxing either the intensity or the scope of her dedication to human rights.

After a performance at Lincoln Center’s Avery Fisher Hall on Nov. 14, Sosa will receive the Anniversary Award from the United Nations Development Fund for Women for her “extraordinary commitment to the world’s women.”

But she is not fond of the fact that she is frequently identified as a “protest singer.”

“Protest songs,” she says, “have become commercial. And, to me, the word cancion de protesta is a childish word. The songs I sing go beyond that, deeper than that.”

Sosa does not write her material, but rather chooses it--sometimes even suggests issues to songwriters--with great care. Nothing she performs is without some special significance.

“My life is what I sing about, not songs,” she says. “I’m always searching and investigating why some people have good lives and other people have suffering.”

Sosa’s questioning springs from personal experience. She was born to a day laborer and a washerwoman on July 5, 1935, in the northwestern Argentine province of Tucuman. Her maternal grandfather was French, her paternal grandfather a Quechua-speaking Indian.

Her parents, like the vast majority of Argentina’s population at the time, were Peronists.

“They loved Evita, and Peron, too,” she recalls. “But they never were militants. And since I didn’t know anything about politics, I was a Peronista , too.”

Sosa won an amateur singing contest as a teen-ager, but she first came to major prominence in 1962 as part of a group of singers associated with nueva cancion. Although there is an obvious correlation with the American music of, among others, Bob Dylan, in the same time frame, nueva cancion was less a collection of protest songs and more a kind of political statement of attitude and feeling deeply connected to Latin America’s revolutionary past.

It is music, it has been said, in which “the guitar is the gun, the song the bullet.”

Sosa takes it even further. “Sometimes,” she says, “I feel like a cannonball.”

Sixteen years ago, when Argentina was controlled by a military dictatorship, Sosa’s songs were making explosive hits upon a government that became increasingly resistant to any kind of criticism.

Initially her performances were banned. When she continued to speak out, in her music as well as in her public statements, the harassment became more severe. A few concerts were abruptly canceled, others terminated by bomb threats.

At one performance, in the resort city of La Plata, government security suddenly charged onstage, arrested her musicians, and forced Sosa to submit to a body search in front of her audience.

Realizing that she could no longer function effectively in her home country, she moved to Europe in 1979. Four years in France and Spain provided rewarding professional opportunities, including appearing at the first Amnesty International concert in London in 1979.

But it was a difficult emotional interlude for Sosa, who lost her voice for a period of time.

“You can only put your clothes and your cassettes and your personal things in a suitcase,” she says. “But you have to leave everything else behind. Your family, your friends, your country--everything that matters.

“And it can be dangerous to stay away for too many years. Because you get used to being out of your country, and maybe you decide to stay and never go back. So you have to return as soon as possible, so as not to lose the link with what you left behind.”

Sosa returned to Buenos Aires in 1982, witnessing the fall of Argentina’s dictatorship and the restoration of democracy under President Raul Alfonsin. The reception that greeted her can perhaps be best illustrated by the fact that her first post-dictatorship album, “Mercedes Sosa in Argentina,” sold nearly half a million copies in a nation with a population of 30 million.

In the last decade, Sosa has sung with such Latin American performers as Milton Nascimento, Chico Buarque and Victor Heredia, as well appearing on programs and recordings with Sting, Bruce Springsteen, Peter Gabriel and Charlie Mariano. Her latest album, “Gestos de Amor,” released last year on Mercury Records, is an unusually lyrical collection of love songs that showcases Sosa’s smooth and sumptuous voice.

Yet Sosa continues to be a controversial figure in her homeland. She has decided, for example, not to perform in her home province of Tucuman.

“The new governor was once in charge of the military,” she says, “and was involved with torture and killing. So I am not going to sing there for a long, long time.”

And although she has not experienced the same harassment she encountered in the late ‘70s, Sosa still has problems.

“I can’t sing on government television,” she says. “It’s the kind of democracy where, if you’re a friend of the president or the people in power, you’re OK. But if you’re not, you can have problems.”

Sosa’s solution is to spend a great deal of time touring internationally--less of a quandary now for the singer than it was when her husband was still alive. Her only child, Fabian, 36, assists with the planning of her programs.

But she has no intention of allowing the situation in Argentina to dilute her powerful convictions or diminish the range of her commitment to justice and freedom.

“I’m a singer,” says Sosa. “And when I’m on stage, I sing. But when I’m off the stage, like any other person, I have opinions. And I have to fight for them, for what I believe in, and for what I believe is right.”

MERCEDES SOSA, Veterans Wadsworth Theater, Veterans Administration grounds, Brentwood. Date: Thursday, 8 and 10:30 p.m. Prices: $36.50-$33.50. Phone: (310) 825-2101.