A night of vibrant soundscapes from Sigur Rós

Lead singer and guitarist Jonsi Birgisson on stage Friday. (Robert E. Klein for The Boston Globe)

The four men huddled around one corner of the stage facing inward, locked in concentration. The sounds that they were making - at that point with thick, churchy organ swells, a gentle swirling bass line, the light chiming of a marimba, and a buzzing guitar - were building in intensity and pitch with vocals ululating in a matching trajectory. The moment peaked, faded for an instant, and zipped off in another direction like a kid chasing a ball. It was both uplifting and a little disturbing. The emotional vibrancy was magnified by the impenetrability of lyrics being stretched beyond the simply foreign into a place designed more for phonetic pleasure than intelligibility. Or at least intellectual intelligibility.

Halfway through the Sigur Rós show at Bank of America Pavilion Friday night, any first-timer trepidation about being bored or put off by aloof, arty pretensions was long forgotten by the time the Icelandic soundscapers were deep into the transporting waves of "Heysátan."

It was easy to imagine how the brass and string sections the group normally travels with would enhance the gauzy atmospherics of its hour-and-45-minute set. But Sigur Rós acquitted itself ably with just the core four diving into the swoony, icy beauty of piano-driven tracks like "Fljótavík" and the more straightforwardly tuneful numbers like "Við spilum endalaust" from the new album "Með suð í eyrum við spilum endalaust" ("With a buzz in our ears we play endlessly").

The group has mastered the crescendo dynamic, with the lion's share of the show's songs building from distant drones to dramatic starbursts of sound that were impossible to resist.

Even though there was a symmetry to the structure of the different tunes, each was decorated individually with the sense of scope ranging from tender miniatures to bombastic widescreen vistas. Two basses beefed up the bottom end of the blue-sky strutter "Hoppípolla." "Saeglópur" built up to a cataclysmic noise fest of grinding guitar and clattering cymbals only to drift off on space pop keyboard fumes. And lead singer Jonsi Birgisson even managed to get the crowd to sing along - the group employs a mix of actual Icelandic and its own personal gibberish dubbed Hopelandic - to his reverb-heavy falsetto on "Með Blóðnasir."

Birgisson, who sports a funky quasi-military jacket with epaulets that Michael Jackson would probably dig, didn't say much between tunes but captivated with his elastic vocals, teasing out long vowels, modulating repeated phrases, and roaming his range to make his voice as much of an instrument as his bowed guitar.

Opener Parachutes plumbed a dream-prog arena similar enough that some patrons arriving during their set were worried the headliner had already taken the stage.