Bjork Gudmundsdottir is one of pop music's great weirdos — a fantastically eccentric songbird who once wore a fake swan frock to the Oscars. She's a wildly creative belter from another planet with a swooping, unpredictable voice that's every bit as singular as her fashion sense.

On her new album, "Volta," the Icelandic chanteuse sounds as otherworldly as ever, setting that tone straight away: The CD opens with a tribal drum pattern and the rhythmic sound of boots stomping in lockstep across a marsh as Bjork yelps, "We are the Earth intruders!" Soon, over buzzing, quavering synthesizer lines, she's unleashing that trans-planetary caterwaul of hers. "Turmoil! Carnage!" she sings, contorting with words along the way.

The tune "Earth Intruders" is a collaboration with the bleeding-edge beatmaker Timbaland and the African groove collective Konono No. 1. In theory, it's a protest song, with Bjork lashing out against warmongering Americans. But it takes something like subtitles to make this clear, as she isn't the most direct lyricist.

She sings mysteriously: "Shower of goodness coming to end the doubt/Pouring over." (In the album notes, Bjork explains that the single is "that sort of fantasy that maybe a tsunami of people would just come and hit the White House and scrape it off the ground and do some justice and spread these people all around the planet." Aha!)

Still, it's enthralling, frenetic and fresh, and it quickly establishes that Bjork, after a decade of meandering experimentation, has returned to form as one of pop's more listenable avant-gardists. She's a restless talent who, in her best moments, can harness her oft-outrageous artistic impulses and turn them into concoctions with something close to mass appeal.

Although "Volta" is more accessible than anything the 41-year-old Bjork has released over the past decade, it's hardly a blatant play for a mainstream audience. The album boasts an undeniable rhythmic appeal, but Bjork's voice remains an acquired taste. It's an idiosyncratic instrument — emotionally raw, dripping with pathos — that rockets from an impish murmur into a full-blown howl.

Besides, Bjork still doesn't do neat, three-minute ditties built around 4/4 beats, pop melodies and standard-issue instrumentation.

"Wanderlust" features Bjork's voice — actually, her voices, as the vocals are multi-tracked, as if she has multiple personalities that need to be heard simultaneously — getting tangled with horns over some skittering digital drums. "I See Who You Are" is an arty lullaby framed by the fractured sounds of Min Xiao-Fen's Chinese lute. "Hope," featuring Timbaland and the Malian kora player Toumani Diabate, has an entrancing, sufi-like quality as Bjork considers a pregnant Palestinian suicide bomber.

And "The Dull Flame of Desire" is a sprawling, woozy ballad in which Bjork trades lines with the quavering-voiced Antony Hegarty, as the all-female brass section fades in and out before the stunning track surges to its conclusion with an explosive, percussive kick.

"Volta," a somewhat political record, also includes a nervy electro-punk rant, "Declare Independence," which sounds like a Riotgrrl screed remixed for the digital age. Bjork issues instructions to start your own currency, make your own stamps, protect your language and make your own flag. And then, over an urgent, bruising beat, she repeatedly barks, "Raise your flag!"

Not the craziest concept she's ever shared.