Experimental metal, also known as avant-garde metal or avant-metal, is a subgenre of heavy metal music loosely defined by use of experimentation and characterized by the use of innovative, avant-garde elements, large-scale experimentation, and the use of non-standard and unconventional sounds, instruments, song structures, playing styles, and vocal techniques. It evolved out of progressive rock, jazz fusion, and extreme metal, particularly death metal and black metal. Some local scenes include Los Angeles, the San Francisco Bay Area, Boston, and Seattle in the United States, Oslo in Norway, and Tokyo in Japan.
Experimental metal has been called the most difficult heavy metal genre to define and describe. However, it is characterized by the use of innovative, avant-garde elements, large-scale experimentation, and the use of non-standard and unconventional sounds, instruments, song structures, playing styles, and vocal techniques. The term "experimental metal" is also often used as a term for the separate genre of "atmospheric metal" or "post-metal", which was named in reference to post-rock. Experimental metal is related to progressive metal, but experimental metal often has more experimentation, while progressive metal usually has a tighter focus on traditional metal instrumentation and higher levels of technical complexity. Experimental metal also uses unusual sounds, breaks conventions, and often includes new elements. The lyrics and visual presentation of the genre are eclectic as well. According to Jeff Wagner in Mean Deviation, electronic percussion and drum machines see widespread use by experimental metal bands, along with female vocals and operatic elements, all of which he attributes to the influence of the band Celtic Frost. The Canadian group Voivod also influenced future bands in the genre, pioneering technique such as robotic vocal effects, unusual time signatures, and fractured, dissonant, unorthodox guitar sounds.
^Fricke, David (5 December 1996). "Aenima". Rolling Stone. Jann Wenner. Retrieved 27 April 2012. "Still, the best parts of Ænima come when Tool just let the music rip and dip with the broiling, avant-metal ferocity of Led Zeppelin's Presence."
^Yuan, Henry (17 April 2010). "Sunn O))) to Curate Roadburn Festival 2011". Revolver. Future US. Retrieved 7 August 2011. "Their metal-based drone experiments have proved groundbreaking and hugely influential for an entire new generation of musicians practicing the art of avant-garde metal, drone, post rock and psychedelia."
^Wilson, Richard. "The Haxan Cloak". Allmusic. Rovi Corporation. Retrieved 19 June 2013. "Distributed by experimental metal label Aurora Borealis, the release earned Krlic a recording deal with the London-based company."