Shortly after her 2001 release of Vespertine, the Icelandic pixie and singer Bjork cryptically said she was still a decade away from creating accurately the music in her head. In a recent interview with Rolling Stone, Bjirk explained that she had spent much of the last year and a half compiling her live boxed set: "The minute it was over, I couldn't wait to make new stuff. I was like, 'That's it for old times!'" And appropriately, it seems she found that catharsis with Med?lla, her fifth album, released last week.

Bjirk has always been rewarded for her refusal to conform. With her immediate interest in then-emerging styles of electronica and house music Bjirk was consistently one of the 1990's' most innovative and exciting artists. If Med?lla is any indication, she may be vying for that title in this decade as well; the album is both daring and accessible.

Keeping instrumentation to a bare minimum, the album is largely a cappella. Instead, Bjirk uses sample and clips of her voice in different situations-squealing, singing, hiccupping, screaming-which she then cuts up and rearranges to create the lush backgrounds to her songs. The result is both intimate and assuming.

To record the album, Bjirk assembled a diverse cast of vocalists: experimental metal guru Mike Patton, opera singer Gregory Purnhagen, veteran art-rocker Robert Wyatt, the Icelandic and London choirs, beatboxers Rahzel (formerly of The Roots) and Dokaka and others. The vocals and beats are layered, spliced, manipulated, and even occasionally left alone.

"Pleasure Is All Mine" may be the singer's most subtle opener to date, as Bjirk gently weaves her delicate vocals through her chorus' slowly building "ooh-oohs." By the second verse, a powerfully operatic baritone has joined the fray, and she begins to unleash her strong vocal range. Bjirk has always employed excess to her advantage, but even the most devoted fans will find it a surprise on such an experiment in minimalism as Med?lla.

Rahzel's pounding beats immediately distinguish "Where Is The Line," and are soon joined by booming choruses, rapid raygun sounds and Bjirk's manic repetition of the question begged in the song's title. Like the most gripping and approachable cuts from Med?lla, "Where Is The Line" ignores the traditional pop format in favor of unconventional structures.

For such a focused project, the album's moods are surprisingly diverse. There is the eerie gloom of "Submarine" (not a far cry from David Bowie's work with Brian Eno in the late '70s), the uplifting pop of "Who Is It," and the erratic house of "Triumph Of A Heart."

Bjirk doesn't entirely adhere to her own rules, either. Scattered instrumentation can be found throughout the album. A gong concludes "Pleasure Is All Mine," a piano is found in "Ancestors." Some gentle synthesizers assist "Mouth's Cradle." But these are never distracting, or even too noticeable; the vocals eclipse the supplemental instrumentation.

In "Show Me Forgiveness" and "oll Birtan" (one of several songs sung in Icelandic), Bjirk enters the recording booth alone, and her piercingly fragile vocals create her most organic-sounding work to date. After spending years surrounded by industry's best producers, she must have found it refreshing to be Bjirk, and just Bjirk, and nothing more.

In her own words: "The pleasure is all mine/to finally let go/and evenly flow.