St. Paul festival kicks off with puckish vocal music by 20th-century rebel Pauline Oliveros

She played the accordion. She earned a black belt in karate. She was a pioneer of experimental music.

Pauline Oliveros is not exactly a household name, but she's unquestionably one of the most consequential figures in 20th-century American music. And now her legacy is being examined by the St. Paul contemporary music group Zeitgeist, with four days of concerts and events set at the group's Studio Z venue in Lowertown.

Thursday's opening night concert was a riveting introduction to Oliveros' freethinking approach to creating musical experiences. Focusing on her vocal music, the concert began with 1962's "Sound Patterns," a work born of an impromptu high school jape when Oliveros and her classmates improvised a selection of clucking mouth noises.

"Sound Patterns" is a more formal distillation of that teen playfulness. Carefully constructed from a combination of "lip pops," "tongue clicks," "snap fingers" and "flutter lips," the piece tingled with the thrill of new ideas. It was ear-poppingly performed by a quartet of soloists who clearly relished its puckish innovations.

Written four decades later, "Sound Patterns and Tropes" developed the seed planted by the earlier work into a fully fledged garden — or perhaps a jungle.

Thirteen vocalists wove a phantasmagorical tapestry of chirps, yelps and primordial mumbles, underpinned by Zeitgeist's four percussion players. Occasionally a scrap of comprehensible language broke surface. Toward the work's conclusion, the voices coalesced in a celestially polyphonic rendition of "Row, Row, Row Your Boat."

Far from seeming chaotic, "Sound Patterns and Tropes" gained cumulative impact as a metaphor for the ceaseless babble of modern living, teeming with an exhilarating mix of raw human energy and occasional desperation. The 13 singers locked convincingly into Oliveros' plan for the piece, which relies heavily on timely improvisations and lies well outside the comfort zone of the typical choral singer.

For "Spiral Mandala," the final piece on Thursday's program, audience and performers migrated down the hall to the Baroque Room, the Northwestern Building's other intimate music venue. There, a ritual circle had been marked out with a bass drum at its center.

"Spiral Mandala" is scored for an ensemble of clarinets, drum and wine glasses tuned to particular notes by filling them with water. In a space dimly lit by candles, a "chanter" moved slowly around the circle, reciting a text as the clarinet and glass players gradually developed a layered texture of drones and pitches above the drum's increasingly insistent heartbeat. The ritualistic effect was palpable, heightened by the headdress and flashing fluorescent bracelets worn by chanter Viv Corringham.

What is "Spiral Mandala" about, exactly? Zeitgeist's thrumming, mesmeric performance suggested it is music of the subconscious Freudian id, a glimpse into darker regions of the spirit where primeval forces reign. In its refusal to pander to conservative expectations of music, "Spiral Mandala" is typical of Oliveros' tirelessly questing artistry. It was a gripping end to a wonderfully thought-provoking evening.

Terry Blain is a freelance classical music critic for the Star Tribune. Reach him at artsblain@gmail.com.