The monks of what was once (until the 1959 Chinese invasion of Tibet) the world's largest monastery have mastered a highly specialized vocal technique. While singing notes near the bottom of the human vocal range, they can simultaneously exercise exquisite control over the overtones in the natural harmonic series--producing what sound almost like chords rather than single notes. Deep, loud, and eerie, the monks quite justifiably call it the "Awesome Voice," and in the company of strident cymbals and the bellow of an enormous horn called the dung-chen, it's the crucial element in the tantric ritual music they'll demonstrate in this program. While in most Western music a succession of notes sounded through time tends to suggest movement forward through space (an analogy expressed concretely in the Western system of musical notation), these monks achieve a quite different effect, a strangely static, shimmering contemplativeness. The function of this music in tantric Buddhism is roughly the same as that of Gregorian chant in the Roman Catholic church, and in the difference between the two musics you can really hear the difference between the two ways of looking at the world. Saturday, 8 PM, Weinstein Center for the Performing Arts, National-Louis University, 2840 Sheridan, Evanston; 708-256-5150, ext. 2593.