In a review of Japanoise: Music at the Edge of Circulation, Scott McLemee defines the genre of Noizu:
The term is a neologism in Japanglish (cf. Franglais) referring to the underground movement or milieu devoted to producing — and enduring – squalls of atonal electronic sound blasted at incredibly high volume. Noizu stands in relation to hardcore punk or extreme heavy metal band something like the roar of a jet engine does to chamber music. Connoisseurs call the sound “harsh,” at least when they are praising a performance or recording.
The “noisician” works with a set of electronic boxes that distort, echo, or clip the frequencies of a sound; they are sometimes connected to one another according to a plan, and sometimes by chance. “Outputs go back into inputs,” [author David] Novak writes, “effects are looped together, and circuits are turned in on themselves. Sounds are transformed, saturated with distortion, and overloaded to the point that any original source becomes unrecognizable.” By the end of the performance, “the circuit is overturned, the gear is wrecked, and the network is destroyed.”
The point is to create, in Novak’s words, “the biggest, loudest, and most intense invocation of sonic immediacy imaginable” — sometimes blasting the audience into “a state of hypnosis, dreaming sleep, or trance.” …[T]he question of whether Noizu is a category of music is a question of taste and, even more, of definition – including self-definition, since there are people in the Noizu scene who insist that it is an experience utterly distinct from music.
(Video: Noizu artist Merzbow)