The human voice is an inherently dramatic instrument. Because it emanates directly from the musician's body, because words as well as notes flow from the singer's mouth, the listener is assured of some sort of theatrical and/or visual experience.

When the voice belongs to a phenomenal singer like soprano Lucy Shelton, the music becomes a gift, message or poem sent from the composer via the performer to the audience. So pure and expressive is Shelton's voice that she could create magic merely by reciting from the song book.

Last night's performance at Baird Auditorium by the 20th Century Consort (of which Shelton is a member) included two works that made exquisite use of her instrument, as well as the talent of the other members of the ensemble.

The first, William Doppmann's "Spring Songs" for soprano, clarinet, percussion and piano, is an erratic but pleasing compendium of styles, texts and effects. The singer accompanies herself on autoharp and the others reinforce her song with spoken words. She whispers, wails with her back to the audience, declaims and rejoices as Doppmann's score shifts from atonality to Renaissance romping to eerie lullabies.

Pulitzer Prize-winning composer Joseph Schwantner's "Sparrows" presented Shelton and eight other members of the ensemble with a ceremonial, thoroughly cohesive theatrical and musical challenge. Set to haikai by the 18th-century poet Issa, the piece unfurls like a dream, all instrumental doublings, vocal oozings, gongs and extended lines.

The program also included George Crumb's "Celestial Mechanics," a percussive experiment for four hands (and sometimes six) on one piano and James Primosch's "Exchanges," in which a subtle relationship is established between flute and clarinet.