MERCEDES SOSA PERFORMS AT SYMPHONY HALL

It's not difficult to understand why the former military government of Argentina banned singer Mercedes Sosa from performing.

Although it's been 10 years since the military government fell and she returned home to her native Argentina after four years of exile, Ms. Sosa still has the presence and vocal power to work an audience into a roaring, fist-waving frenzy of the type usually reserved for rock stars. The young, informally clad, and largely Spanish-speaking crowd at a recent concert in Boston's Symphony Hall was no exception.

Sosa bridges different musical styles, from flamenco to jazz to Andean folk. The latter is the driving force in the high-energy "Taki Ongoy II," which she played near the end of the Boston show. It is a song of indigenous rebirth: "And on the earth will fall/ an endless rain/a great deluge/ that drowns the pain/ of so much death and desolation/ to fertilize our rebellion."

Even without the knowledge of Spanish needed to reveal the political and social basis of Sosa's lyrics, one could hardly help being captivated by her performance. Though she usually sits quietly while singing, her voice seems to contain the full power of the reawakening indigenous peoples of the Americas. And closing one's eyes, the electronic echo effect makes it possible to imagine hearing her voice reverberating around a mountainous Andean village.

As Sosa throws her head back in laughter or slowly dances around the stage, her joy in the music and her connection to the audience are clear. The watchers become the watchees as floodlights illuminate the house.

This is powerful music - no wonder governments tremble.