Who knew, but Sigur Ros are actually hugely popular. To those who’ve only sporadically followed their career — perhaps coming up against Ágætis byrjun in smoke-filled college dorms or re-discovering “Starálfur” in that pivotal scene from The Life Aquatic — the band seem like an odd success story. They don’t sing in English. Their songs are often amorphous and subtle, or else build up during a single, long crescendo. Sure, Jónsi Birgisson’s falsetto is raw and beautiful, but is it revelatory? This seems like a silly question to anyone who’s seen the band live. Or even to those who’ve spent afternoons listening and re-listening to the group’s ethereal music through noise-cancelling headphones. The truth is that the Icelandic quartet transcends language and taps right into emotion. And, after seeing them in Sydney, it’s clear that Sigur Ros have also become expert performers. Fourteen years into their career the touring schedule seems to only have become more intense; this was their third trip to Australia in as many years, and they’ve been just as ubiquitous in Europe and the States. So, what makes an expert performance of Sigur Ros songs? Luckily for the band, the communication of their trademark emotion requires little direct audience interaction. That unease with engaging with fans (at “putting on a show”) was demonstrated in the film Heima, released last year on DVD; and apart from a few words in Icelandic and a “thank you” or two, the band cuts a silent, stoically eccentric presence on stage. But talk is not necessary. Instead, the band relies on its wavering, enveloping compositions, the majority from 2005’s Takk and this year’s Með Suð í Eyrum Við Spilum Endalaust. And vitally, the group displays not an ounce of ironic detachment. Sigur Ros songs walk a dangerous line between strong emotion and melodrama; anything less than the reverent attention the band pays them onstage might cheapen the impact. Perhaps as a way of countering the horrible, barren atmosphere of the Hordern Pavilion (the place feels like a large warehouse, boxy and temporary, with exposed pipes and makeshift plastic seats around the edge), the group opened with some of its most inviting material, specifically “Svefn-g-englar”, off 1999’s Ágætis byrjun. And here’s where having a roomful of awed fans makes a huge difference to everyone’s experience of the show. Sigur Ros doesn’t play the kind of show where the audience sings along to material before it’s been officially released. (It’s difficult for anyone to sing along to even the band’s most well-recognized singles). But complete silence, as echoing guitars fade down, has its own electricity, and the tinkling sound of a glockenspiel was enough to make that palpable. Tonight, Sigur Ros performed six songs off their new album, the majority towards the end of the set (the contemplative “All Alright” serving as the final, second encore). The contrast between this new material and the older, more ambient and enveloping songs was highlighted by the group’s backing band — the Horny Brasstards, a cheeky marching band, which replaced the string quartet Amiina, who provided swirling string accompaniments on past tours. The trumpets, trombones, and accompanying horns emphasized the more straightforward choruses of “Við Spilum Endalaust” and “Inní Mér Syngur Vitleysingur” with glorious fanfares (though you still wonder what “Fljótavík” might sound like if, say, both Amiina and the Horny Brasstards were to join the group for one huge night). But it’s the experience of hearing these songs live, interspersed with the older material, that allows us to place the new album, Með Suð í Eyrum Við Spilum Endalaust, more comfortably alongside its predecessors. Sure, it’s poppier and more traditional than anything Sigur Ros has done before. But don’t read “Gobbledigook” as a new direction, more as a happy excursion. It’s a poor choice for single, because though it’s catchy and accessible, and it highlights the optimistic turn the group’s taken, it’s not really an accurate indication of what Sigur Ros currently sound like. But as the big finale to their live show, it is overpowering and uplifting. As confetti rains down, behind giant orbs of multi-colored paper lanterns, the band and the brass accompaniment pummelled drums with a purely celebratory energy. This sort of spectacle suits Sigur Ros’ sound — it is why, for example, their music works so well as the accompaniment to epiphanies, revelations, or climactic scenes of films. And the group relies on the bombast of a crescendo reached — crushing layers of bowed guitar, horns, and drums, with looping falsetto vocals — to emphasize the cathartic emotion of its songs. More surprising is that the jammy middle sections of some of the material from Takk holds the audience just as rapt, and that the eclectic and uplifting new songs, though less well-recognized, when performed live become a coherent foil and a substantial pleasure in their own right. Together, for a portion of this Australian audience — and, you suspect, for this band’s audiences throughout the world — all that came remarkably close to a revelatory.