The Siberian baritone Dmitri Hvorostovsky gives new meaning to the term ''heavy breathing.'' No, not just because he has been one of the opera world's hottest pinups virtually since 1990, the start of his international career. The term also applies to his singing. Few singers have such great breath control. In practice, Mr. Hvorostovsky's involves a sometimes rough inhalation followed by a long arc of warm sound.

The paradox of opera singing is that it requires an extensive and to some degree artificial skill set, developed over a period of years, but also relies on a natural force: the raw power of the human voice. When a singer can establish a balance between those elements, it's akin to the dam of a hydroelectric plant channeling the force of a river into electricity. Mr. Hvorostovsky's voice, solid and extending easily up and down the scale, retains a sense of raw wildness beneath the sophistication of his artistry. It is, in a word, electric. In an age of increasingly overcultivated, mannered voices, he is a breath of fresh air. He just sings.

And he makes you want to hear him. Recently signed by the small label Delos, he has explored different avenues, most recently the original crossover repertory favored by tenors in the early days of recording: Neapolitan songs. On ''Passione di Napoli,'' he delivers some with intense darkness, as if they were opera arias, in an exultation of sound. He brings a selection of them to the Mostly Mozart Festival on Thursday, with the Moscow Chamber Orchestra conducted by Constantine Orbelian at Avery Fisher Hall.