Ever heard of mouth music? It's a traditional technique for producing music with nothing except rhythmic vocals -- literally, just music from the mouth. Quirky Icelandic Bjork isn't a Celt, but she takes the term "mouth music to new heights in the enchantingly challenging "Medulla," an album whose music is based on the voice.

Bjork embarks on her strangest and most experimental musical journey here. Not just one kind of song, but many -- majestic medieval-flavored music to pop to hymns to an eerie vocal ballad backed by throat singing. Bjork even beatboxes with a choir behind her, giving a sort of classical hip-hop sound to the music. Can't get that just anywhere.

"Medulla" isn't entirely devoid of instrumentation... the non-vocal variety, that is. There's a pretty piano solo to "Ancestors," and the deep bassline of "Submarine." Keyboards pop up occasionally But those are the exception -- most of the time it's Bjork's soft vocals, singing, grunting, whistles, and various gutteral sounds -- sort of a dolphin-on-acid noise. It's wonderfully weird.

After the pretty but vaguely monotonous "Vespertine," Bjork just bursts out with her new sound. What's strangest is the effect it has when one is listening to it -- it's powerful and visceral, lulling you one moment and making you shiver the next. At times it's unnerving -- the grunts range from sexy to ghastly, and are enough to make you squirm -- but it never fails to provoke a response.

"Medulla" isn't a full departure from her past material. The opening number has echoes of "Vespertine," while "Where is the Line" hints at "Homogenic." But the heart and soul of "Medulla" rests in an entirely new zone, far away from the icy grandeur of her past trip-hop. This is a darker, thicker sound, backed by Robert Wyatt's odd vocals and a choir.

Bjork proves again that she is an artist in every sense of the word -- she doesn't just make wonderful music, but she explores into new and thrilling musical arenas. Revolutionary, sultry, and a jolt to the system.

I was in a funk all day after listening to this album for the first time. Being a Bjork fan (almost verging on obsessive) for over 11 years, to say that I anticipated Bjork's next release is an understatement.

I can tell that I am not going to be popular given all of the 5-star reviews already posted but can see that I am not entirely alone in being utterly disappointed. Bjork is truly one of my favorite artists but I am not so enamored by her that I will convince myself to like something that I don't just because she is the one who created it.

Most of the tracks would be listenable were it not for the hyperventilating, moans, cries, and wails that make some tracks almost laughable. In fact, some of them I did laugh (especially the track Ancestors!), thinking to myself "You've got to be kidding me!". Although some songs have stuck in my head and provide a glimpse of the "old" Bjork in all of her glory, I was hoping for an album that I couldn't wait to listen to over and over again, that would satiate me for the years of wait until her next album. I did not find this in Medulla.

She has said that she felt cleansed after completing this album and I sure hope she got it all out of her system because if the next album is like this one, I don't know what I'll do.....

Having known Björk's music for a while, it is easy for me to understand where Medúlla's perspective comes from. Her endless need to reinvent herself, spinning world after world out of each project's sonic ashes, makes sense to the listener that hears the intimacy in songs like 'Pagan Poetry' and 'Jóga,' or the raw intensity in 'Hidden Place' and 'All Is Full of Love.' To the casual ear, though, this latest album may sound more like a series of a capella experiments, warmups, and even alarming mistakes. It is a fascinating listen, but an alienating one for the uninitiated.

Her spectacular first single, the Athens Olympics debuted siren call 'Oceania,' may have impressed many and confounded a great many others (Poor Katie Couric!), but her decision not to release it commercially is telling of her idiosyncratic view of music in general. Songs like 'Triumph of a Heart' and 'Mouth's Cradle' are both instantly recognisable as patent Björk magic and incredible sonic journeys, but digressions like 'Ancestors' and 'Miðvikudags' (Icelandic for Wednesdays) may confuse or even frighten. Her interest in paganistic, primal grunts and whistles is compelling to hear about, but disarming to listen to. That, in general, is the sense one will be left with after listening to most of these songs, sadly. But there are a number of worthy gems to be found, 'The Pleasure Is All Mine' and the e e cummings-based 'Sonnets/Unrealities XI' being remarkable examples.

Björk is a leader in her field and a master of innovation. But Medúlla is a departure many fans will have a difficult time following along with.

Look for the second single, 'Who Is It,' to come out on October 25.

I heart bjork. some of the songs creep me out but that's awesome.

Pleasure Is All Mine [10/10]: A beautiful and understated way to start the album. Medulla's principal performers - Tagaq, Rahzel, The Icelandic Choir, Mike Patton, and of course, Bjork - are quietly introduced in a tightly formed song with a dark, highly sensual tone. Never one to take the easy route, Bjork injects three breaks of varying length in the track - beginning, middle, and end - featuring some great vocal layering between her and Tagaq (who's breathing works really well here). This track is strong on it's own, without these interludes, but Bjork's re-structuring demonstrates why she has continued to produce such fresh and inspiring work. PIAM is second only to Vespertine's "An Echo, A Stain" as the sexiest song she's made, in my opinion. The lyrics are quite inspirational as well. It's fascinating the way she can make a song that is dark, warm, cool, sexual, romantic, and nurturing all at once. This track perfectly captures the essence of the album - it truly does sound like it's made of a black ink-like liquid.

Show Me Forgiveness [6/10]: A capella Bjork. On first listen, I found the melody too disorienting. But after a couple of listens - especially when she hums the tune in the second half - it becomes clearer and more compelling.

Where Is the Line [8/10]: How do I describe this one? Maybe a cross between a capella heavy metal and the soundtrack to the Omen. It's certainly bold and curiously fascinating. I'm just having a hard time knowing what to do with this track. Though I will say that this track really kicks a** when played loudly on a good sound system! Having read some of the other reviews, it's interesting to see how many people seemed to instantly love this track. Usually I am able to find some really wonderful settings or contexts in which to listen to a particular Bjork song or album. For example, Vespertine is a great soundtrack for when I'm hanging around the house on the weekend or taking a walk some place with a lot of vegetation. I'm not sure what setting would work with this song ... some place with very little light; near a blazing fire; who knows? It could probably work really well performed live. I do like that part after the whistling, when Mike Patton and/or Gregory Purnhagen go nuts, Bjork's vocal distorts, and later, Rahzel makes some heavy pulsating sounds.

Vokuro [9.5/10]: Absolutely gorgeous. This song nearly brought tears to my eyes the first time I listened to it. The choral arrangement of this Jorunn Vidar piece is powerful and timeless.

Oll Birtan [9/10]: Performed by several Bjork vocal layers. Much more earthbound than Vokuro, but nonetheless quite gorgeous after a few listens. I picture a girl running through a field, perhaps on her way to school or passing a small chapel.

Who Is It [10/10]: Yeah!!!!!!! This song is totally sublime!!!!!!!! It's Bjork at her avant-pop best - at the top of her game. She and Rahzel make a terrific pair. Some elements of the song that deserve the highest praise: (a) Bjork's ability to create a great pop song. Who else is able to convey such a pure joy? Her bass synth (and Patton's performance of it) is wicked too. (b) Rahzel, Rahzel, Rahzel!! This song definitely utilizes his amazing beatboxing talents best. He is absolutely integral to the song. Even if he hadn't performed this track in one take (as Bjork noted in an interview), his work would still be amazing here. He deserves credit for creating in this song what are probably Bjork's best beats in all of her work. (c) Bjork's vocal delivery on this track is really solid. One of the problems with some of her best pop songs is that the strength and nuance of her voice gets somewhat undermined by the instrumentation/electronics (examples: Hyperballad, Possibly Maybe [album version], Alarm Call). Although the song is fairly straightforward in terms of Bjork's vocal, she does a great job here, and the engineers/programmers got the balance just right here. (d) Those chords comprised of Bjork vocals that sound like some old pipe organ or something. They're the icing on the cake.

Submarine [8/10]: Robert Wyatt's collaboration with Bjork. Wyatt has such an incredible voice - it's reedy, vulnerable, old, watery, all at once. I'm glad that Bjork allowed him to sing most of the song. (I get so tired of the traditional duet - you know, the kind that Celine Dion loves - in which it serves as a lame excuse to feature stars who pretend to be in love or whatever.) This is a very intriguing a capella piece. It's mostly Wyatt singing here, until there's a sudden 30-second outburst by Bjork about half way through the song. It's an interesting touch.

Desired Constellation [10/10]: Wow. This is a masterpiece. This is easily one of the best songs Bjork has ever made. Everything about this track works exquisitely: (1) Bjork's vocal is very strong, very simple, but it's one of her best deliveries. She's very confident here. She sings the same line over and over again, but she does it so well that you want to keep hearing the small changes she makes each time. She's so comfortable that she occasionally adds a heartbreaking sustained note in between this repeated line - a sign of how incredibly generous she is to this song. She must know what a gem she's created here. (2) Her collaborations with Olivier Alary/Ensemble are truly remarkable. Because their previous collaborations - Sun in My Mouth (recomposed) and Coccon (retangled) - were both remixes, the one ingredient missing from them was Bjork's direct response to the music (though they are still two of her best remixes). Here we see how well she works with Alary's soft, distorted, free form meanderings. It's also nice to hear an electronic composition that is bare enough to allow the listener to catch the subtlety of Bjork's voice. Truly stunning.

Oceania [10/10]: Breathtaking ... another of Bjork's best compositions to date. The second I heard the first choral sweep arpeggio I was swept off into this gorgeous aquatic landscape. Again, Bjork's vocal delivery is ace. And Sjon's lyrics ... they're some of the most beautiful I've heard in years! I'm serious!! Bjork could not have created a better song for the Athens Olympics.

Sonnets/Unrealities XI [8.5/10]: This is a nice adaptation of E. E. Cummings. Bjork's abilities with choral arrangements are becoming really impressive. This would make a good side project for her: adapting a series of E. E. Cummings poems. Along with Vespertine's "Sun in My Mouth" and the b-side "Mother Heroic", she's now made three very good ones.

Ancestors [7.5/10]: Hmm ... It's been a year since the album was released and I'm still not quite sure what to make of this one. I do admire Bjork for including this on the album because she clearly appreciates the work of Tagaq. It's also admirable that she has the confidence to include this in the same record that has some very catchy pop songs. The last minute of the track is absolutely amazing - it's very primal. The final collaborative breath between the two women is devasting.

Mouth's Cradle [9.5/10]: This song really grew on me. It has a very ancient, primitive sound to it - very heavy, muddy, creature-like. The choral arrangement is spot-on here. All the vocal layers work especially well together in this composition.

Midvikudags [9/10]: Another gorgeous all-Bjork vocal arrangement. Has a very vernacular yet accessible feel. Some of her vocal layers sound very flute-like.

Triumph of a Heart [6/10]: A somewhat disappointing way to end this stunning record. This song already has many fans on Amazon, but I definitely can't say that it's one of my favorites on this album. In fact, I find it a little disappointing because, basically, all the elements are there, but it just doesn't quite work as well as it should. A couple of reasons I think this might be the case: (1) It just doesn't have a very catchy melody/chorus (not that every Bjork track needs one, but this track should have one). This song isn't nearly as downright funky as "Who Is It". (2) It sounds too faux-electronic. On all the other tracks, it is clear that Bjork's intent was not simply to replace instruments with human voices; here that distinction is not as apparent. As I said, many of the isolated elements are pretty good fun: Dokaka and Rahzel do a great job on their own, but the song is just not quite there to support them.

Overall, this is an incredibly bold statement from the ever-courageous Bjork. This is the first record I've ever heard that truly brings to mind such things as blood, wood, ink, mud, bones, and flesh, among other things. Not only that, Bjork is at the top of her game on some of these tracks, both as a composer and singer. The production really brings out the fascinating timbres in her voice. Bjork deserves enormous applause for her tireless exploration of musical boundaries.