No matter where you were on Earth on May 17, chances were pretty good that you could listen to the new Sigur Rós album at 7 p.m. local time.

Prior to the May 29 North American release of the Icelandic post-rock band's sixth studio work, Valtari, the group hosted a rolling, hourly event so that fans across the globe could hear the new full-length album at more than 40 indie record stores, on a dozen participating radio stations or at the band's official website. Fans were encouraged to post to Twitter and Instagram about their listening experience using a special hashtag, while each store listener entered a raffle to win a Valtari prize pack, courtesy of the band's label, XL Recordings.

Sigur Rós bassist Georg Holm says the ­marketing stunt helped ensure that Valtari was experienced as a whole by fans. The group's last album, 2008's Með Suð í Eyrum Við ­Spilum Endalaust, was an uptempo offering heralded by the rollicking single "Gobbledigook" (32,000 downloads sold, according to Nielsen SoundScan), but Valtari is a slower, more orchestral effort.

"It's not something where you can only listen to track three," Holm says of the set. "We've never had as much discussion about an album's track listing. We've never given it this much thought."

The music's creation was just as painstaking. According to Holm, the group started working on the album in 2009, but gave up on the new songs because they "just didn't fit together." During the three years the band took to make the eight-track album flow, singer Jón "Jónsi" Þór Birgisson released his 2010 debut solo album, Go, and a live film ("Inni") whose soundtrack album arrived in November.

Valtari was officially announced in late March-and promptly leaked online in mid-April. To reclaim the buzz for its street date, XL VP of marketing Adam Farrell says the label wanted a "mass-media event that tied in record shops, radio and online in a compelling way." The feedback to the album's global listening party was, according to Farrell, overwhelmingly positive from all involved. "The record stores and NPR affiliates embraced it as their own thing," he says.

With the event, also known as "Valtari Hour," now just a memory, Sigur Rós will bring its new material to a handful of summer festivals, including Lollapalooza, Outside Lands and Japan's Summer Sonic, though the album's viscous flow is admittedly more conducive to hushed quarters than outdoor music events.

"We can't play all of the songs from this record because they're very quiet," Holm says. "You don't want some techno tent next door making it difficult."