wide angle: Imagine a hypothetical debate about Pantera [ tickets ]'s new album, "Reinventing the Steel" (Elektra), its first studio assault in four years. On one side of the line, envision the band's fans. They are thrilled to hear that the playing on "Reinventing" is bracingly tight; they are awed by guitarist Dimebag Darrell's array of buzz-plane, weed-whacking, wah-warped sounds. Now contemplate the other warring camp, the critics of heavy metal. They dislike the genre for its static rhythms, cliched minor-second riffs and stereotypical imagery.

But if one avoids the debate and instead studies Darrell's guitar sounds, one finds that his extremes of volume and distortion share common objectives with other forms of music. These forms--metal, free improvisation, modern classical and others--all use disturbed sounds and experiment with an aesthetic of irrationality, though they differ in degree. They also create contexts for the extreme sounds, and this is what determines the final effect the music has on the listener.

Darrell seems to try for guitar sounds that are new (to him)--for example, his last solo at the end of "Goddamn Electric," which might be described as an extremely overdriven theremin-like sound crossed with a piercing radio signal that can't be tuned in. The same can be said of guitarist Nels Cline [ tickets ], who also went to extremes of distortion and feedback on last year's "Interstellar Space: The Music of John Coltrane" (Atavistic). Pairing Cline with drummer Gregg Bendian [ tickets ], the disc is a set of no-holds-barred improvisations that don't clearly fit into the free jazz or jazz-rock fusion genres. Darrell is similarly extreme in his piercing, descending-scale riff and his main guitar part on "You've Got To Belong To It," in which he wavers his pitch as if he's slowing down and revving up a table saw. These are examples of heavy metal's connection to machine sounds and sonic sources that seem to be malfunctioning or disturbed.

Consider several genres in which guitarists use "sick" riffs and longer extrapolations of them: heavy metal music, industrial music (like Nine Inch Nails' grinding guitars), rap-metal (Tom Morello of Rage Against the Machine is a creative model), exploratory improv, and ''virtuoso rock'' music (Joe Satriani is representative). Though some of these instrumentalists are more successful and more interesting than others, they create sonic extremes for common reasons. They are responding to sources that exist in the sonic environment already. They are part of a century-old aesthetic movement in which it's acceptable to bring "noise" into "music." They all are able to obtain the sounds quickly because the guitar's basic output is easy to control and manipulate. (An overall sound that is not created by pedals or computers, such as guitarist Derek Bailey's stridently polytonal playing, is harder to come by.)

Although these musicians may reach for the same extremes, the contexts that they create for their sounds are different. In the case of Cline and Bendian, the two players collaborate and spontaneously create their musical forms; there are no set parts or beginnings and endings. Satriani's "Engines of Creation," uses computer-programmed rhythms and is layered in the studio; the context doesn't give interactive roles to other players. For Pantera, the context is controlled by set parts that are worked out in advance.

Heavy metal uses very conservative forms and rhythms--a crowd of bobbing heads or the march-steps of moshers indicate them visually. But in the space of the guitar solos, the player using volume and distortion has the freedom to stretch out and even create intentionally dissonant and unmelodic music. This explosion comes across as unusual because the rest of the music is highly-structured.

In an extreme metal solo, the guitarist allows some irrationality to creep into the process, without abandoning control completely. This is a miniature version of a fifty-year old musical idea in which a player can create new music by not trying to control the result. In metal and guitar-hero music, this impulse is confined to some thirty seconds in the solos, which are perfected over numerous takes, then usually reproduced live. Other forms of music relinquish control more completely and for longer stretches. Saxophonist Dan Plonsey [ tickets ]'s disc "Ivory Bill" (Music & Arts), which contains overdubbed saxophone compositions inspired by bird calls, is an excellent example. Plonsey uses parts that had to be played impossibly fast and also writes lines that intentionally sound off-key (too flat or sharp to our Western ears). One of his goals as an improviser is to allow errors so that idiosyncratic sounds would be produced.

Pantera's brief illuminations of the electric fringe are weighted down by the inherent characteristics of the heavy-metal genre. The basic form of the music uses the power-chord riffs, a select range of white-noise distortion and unsyncopated double-bass drumming. Though the band is musically creative in its genre (the lyrics are another topic), Darrell's guitar work does not have the context around it to accomplish other extreme sonic effects. Composer Glenn Branca has written droning rock symphonies which are louder than Pantera; one of his musical intentions was to produce unusual series of overtones. (Atavistic has released several of these symphonies).

But Pantera manages to perk up the metal genre at times, using several prog-rock-influenced riffs on the new album's cut "Revolution." Darrell and drummer Vinnie Paul have recently recorded some hoe-down thrash metal with outlaw country singer David Allan Coe--a very different melodic voice than that of Pantera's Phil Anselmo, who growls demagogically. Perhaps beyond Darrell's solos, there are some embryonic explorations in Pantera that will eventually drop down the fallopian tubes and cry out for new ears.