Album: Various artists

Scratch, Transparent

With the DJ, long regarded as a vital to hip-hop culture, now accepted as an equal member in rock bands like Limp Bizkit, scratching has become a ubiquitous element of modern pop, to the extent that turntables apparently now outsell guitars. So far, only DJ Shadow has made much headway in establishing himself as a solo scratch artist, but this soundtrack to the award-winning documentary chronicling the evolution of the form features other performers with equally dazzling skills.

There's Rob Swift, studding the beat of a Don Cherry loop with spat-out vocals on "Re-Animator"; Mixmaster Mike and DJ Disk, blending fluttery drumbeats and quacking scratches like a cross between a duck and a synthesiser on Praxis-Warszawa; and, best of all, a whole host of turntablists tearing up Herbie Hancock's "Rockit" into an eight-minute scratching tour de force, the DJ equivalent of pass-the-mic freestyle rapping. It reveals the form as the sonic counterpart to Cy Twombly's scribbled artworks, a tangle of sound developing its own aesthetic logic as it proceeds. But like lead guitar, scratching is most effectively used in small doses to spice up a track; over the course of an entire album, one overdoses on it: it's akin to being bludgeoned into submission by a sidelong solo from some blues-rock guitarist, prompting comparable questions about the relative values of speed, technique and emotional impact.