Noise music is a term that succinctly sums up this genre by its name alone. Noise music is loosely related to industrial, sharing its DIY ethos, independence and ethic of using "non-musical" sources. Often punishing and abrasive, Noise music can be difficult listening, ranging from the free-form extreme electronic music of Whitehouse and Merzbow to the more sculptured sounds of Otomo Yoshihide.
Fans of the genre distinguish between "pure noise", with essentially no structure, and "rhythmic noise", which contains elements of conventional musical structure, especially rhythm. Many industrial and electronic artists incorporate noise elements into their work.
For reasons unknown the genre became popular in Japan, with a large following in Tokyo and Osaka. Musicians such as the afore mentioned Merzbow, Otomo Yoshihide and other names like KK Null, Masonna, The Gerogerigegege and The Boredoms have made this nation something of a mecca for this style.
Lou Reed's quad LP album Metal Machine Music released in 1975 is an early, well known example of noise music. Despite speculation that Reed intended it only as a way to get released from his record contract, he himself insists (for what this is worth) that he was "very serious" about this work. Certainly Lou Reed must have been familiar with the work his Velvet Underground cohort John Cale had done with electronic drone music with artists such as Tony Conrad and LaMonte Young in the mid-60s (see the CD release of Inside the Dream Syndicate Volume 1: Day of Niagra).