NYMPH, a strange, experimental band from Brooklyn, gives you a kaleidoscope view of how to work out a riff. Formed around the duo of guitarist Matty McDermott and vocalist/percussionist Eri Shoji, and filled out on the album by Nickle Emmett on bass and Jason Robira of Dark Meat on drums, NYMPH boils down the song to extreme riffage by discarding other aspects of typical pop songwriting. There are audible elements of free-jazz, noise, and drone influences; there are even some international folk forms added into the mix. But what NYMPH does best takes its cue from guitar-centered rock. Now, the Social Registry has made their self-titled debut from last year more widely available.

Since NYMPH is primarily a guitar band, you would expect more shredding. NYMPH focuses on the riff, but not in a typical macho sense, McDermott exhausting his guitar lines to the point where you don’t want to hear any more. The key to a good riff is its repetition value. Of course, riff-repeat-ad nauseam gives you a boring song. But NYMPH manages to repeat riffs while still remaining interesting (for the most part). The riffs are too long or too short to really fit into pop song structures. By tweaking them slightly in repetition, McDermott critiques the whole riff-centered process. The possible downside to NYMPH’s focus on repetition is the eternal question of avant-garde self-indulgence: Is the innovation good enough to make the repetition interesting?

Shoji adds yelps and squeals that accent the guitar but never take the typical aural space of a rock band’s lead vocals. Her vocal delivery blends Ponytail’s gibberish with Deerhoof’s cuteness. Together, McDermott and Shoji create a half-crazed, energetic sound that confounds expectations even in its repetition. But the real interest is always the guitar; McDermott’s sound is wonderful: just the right overdriven edge, just the right amount of reverb. NYMPH never actually gets to improvisation or anything truly jazz-like, though there is an obvious influence of free jazz here. The guitar always explores its sound in rock mode. It would be drone if the notes didn’t lift it into an almost lyrical level.

The album is made up of five songs. The first and last, “Ii-Yo” and “Namu”, are NYMPH at its most interesting; a hard riff, surrounded by crazy drums and yelps, drives both tracks through ten to 20 minutes of thorough exploration. The middle three songs take a more mellow approach, introducing different instruments (clarinet and—lo and behold—acoustic guitar).

The middle songs, while slightly boring, provide a necessary relief from the onslaught of the bookending tracks. “Reeds of Osiris” initiates the completely different tone that makes up the album’s center. Over a swinging tom-heavy drum beat and chiming bells comes a squonky clarinet (the reed of the title) like a strange forgotten character from Peter and the Wolf. “Snow Song” continues the rhythm of “Reeds”, but the guitar plays a more traditional rock-sounding melody that Shoji accents with breathy squeaks. “Bird Song” shifts to acoustic guitar with a shorter melodic line than the other songs. Its repetitive drone indeed begins to sound like a bird call—witness Shoji’s “hoot hoot hoot”.

“Ii-Yo” shows you what NYMPH is capable of, but “Namu”’ capitalizes on this promise. The songs begin with a guitar line (fairly similar in both) that gets worked out in all its possible mutations for a collective half hour. Nothing strays from the center path, though the rhythm builds and breaks, the riffs twisting and turning. The long form lets the band go full-on, expanding and contracting the repeated sections, going crazy and breaking down in a journey to run the song into the ground. You can imagine McDermott running up and down the fretboard with the riff, plotting out the linearity of its melody in geometric shapes of slightly different intonation, while Shoji shakes and squeals, ringing bells and yelping in response to each nuance of the guitar.

Though these songs are repetitive, you never know what’s coming next. The songs are completely held together by riffs. McDermott and Shoji could attack from anywhere—any note or melody. However, despite the apparent free form, the songs are pieced together by well-defined parts that follow a pattern.  Even though NYMPH does away with traditional rock forms, the sound is fairly monolithic. These guys are sufficiently weird to keep the music interesting, but the band will only get better the more comfortable McDermott and Shoji feel in really letting themselves go and adding more improvisation to their experimentation.

• Multiple songs MySpace