About 9 o'clock Tuesday night, the pummeling noise-rock band Swans took the stage of the Trocadero. About 9:10, they played their second chord. In between, Michael Gira, the band's only constant member, and five cohorts pounded rhythmically at a single note, repeating it three, five, 10 times in a coherent but unplaceable pattern.

At one time, Swans, whose roots lie in the same New York subculture that spawned Sonic Youth (whose Thurston Moore was an early Swan), were known less for their music than for the volume at which they played it. They were so loud that many fled the room, while others fought a sick feeling in the pits of their stomachs.

Gira, 56, disbanded Swans in 1997 after a 15-year run, citing his fatigue with their endurance-test rep. But after more than a decade leading the relatively docile Angels of Light and playing shows with (horrors!) only an acoustic guitar, Gira announced earlier this year that Swans would return, although he insists that it is not a reunion but a continuation.

Tuesday's 75-minute tour-opening show, the same day as the release of the new Swans album, My Father Will Guide Me Up a Rope to the Sky, never strayed too far from its opening salvo, appropriately titled "No Words / No Thoughts." But the endless repetition was trancelike rather than monotonous, a ceaseless onslaught that made the room vibrate like a tuning fork.

Gira's songs are brutalist rather than primitive, with just enough variation built in to let you catch your breath but not enough to let the spell dissipate. On "Your Property," drummer Thor Harris quickened the pace with a sixteenth-note skitter that came close to swing. The wave broke during "Sex, God, Sex," but only long enough for Gira to "Praise the Lord, Jesus Christ" with an anguish that made salvation seem like the lesser of two evils.

In the end, though, the feeling was less one of assault than of cleansing, as if the audience had been scoured clean. Gira's thoughts may be ugly, but the sound was oddly beautiful.