Experimental music consciously deviates from established musical norms (of a particular genre, or of music in general). Music of almost any genre can be considered experimental, but the term is often associated with the more abstract and challenging strains of Electronic music, Jazz, and Rock.

Experimental music might explore new compositional techniques, new musical forms, unusual instruments, extramusical sounds, “extended technique” (playing instruments in unusual ways), microtonal scales, minimalism, unexpected stylistic fusions, abrasive timbres and rhythms, or experiments in any other aspect of music.

As such, “Experimental music” isn’t really a single style with a distinct sound. It’s more of a sensibility: an effort to explore new musical frontiers, and to expand the boundaries of musical experience.

Experimental Rock is a term applied to music in which artists abandon Rock conventions and opt for an exploratory approach through experimentation with song structures, uncommon time signatures, rhythm, dissonance, instrumentation, noise, electronics, and other techniques. The most extreme acts incorporate Experimental music traits, such as improvisation, non-traditional production, and studio manipulation methods.

Experimentation in Rock started emerging in the mid-1960s, thanks to developing recording technology, such as mixing consoles and multitracking’s popularization.

The Mothers of Invention featured a mix of orchestral instrumentation, quirky, satirical humor, avant-garde influences, and styles such as Jazz-Rock, Rhythm & Blues, and Psychedelic Rock. Though initially a Blues Rock act, Captain Beefheart & The Magic Band utilized unconventional composing processes, clusters of polyrhythms, and complex interplay. The Velvet Underground blended raw production, feedback, drones, drug culture-inspired deadpan vocals, and popularized the ostrich guitar tuning, while Silver Apples and The United States of America discarded guitars and utilized oscillators, keyboards, strings, and primitive synthesizers.

From its inception, Rock music was experimental, but it was not until the late 1960s that Rock artists began creating extended and complex compositions through advancements in multitrack recording. In 1967, the genre was as commercially viable as Pop music, but by 1970, most of its leading players had incapacitated themselves in some form. Also, in the late 1960s, German social movements developed Krautrock in revolt against foreign commercial music, where merged elements of improvisation and Psychedelic Rock with Electronic music, Avant-garde and Contemporary Classical pieces.

Later in the 1970s, significant musical crossbreeding took place in tandem with the developments of Punk and New Wave, DIY experimentation, and Electronic music. Funk, Jazz-rock, and fusion rhythms also became integrated into Experimental Rock music. In the mid-1970s, Post-Punk emerged, adopting Punk Rock’s DIY ethos but quickly separating sound-wise. Many bands from the initial wave integrated influences outside of Rock and experimented with complex rhythms and intricate songwriting, with groups like Public Image Ltd., The Pop Group, and This Heat incorporating Dub, Funk, Free Jazz, and Industrial influences. In the late 1970s, the No Wave scene emerged in downtown New York, where acts such as DNA, Contortions, and Glenn Branca discarded melodicism and relished in dissonance, atonality, and skronk.

Early 1980s Experimental Rock groups had few direct precedents for their sound. Later in the decade, Avant-rock pursued a psychedelic aesthetic that differed from the self-consciousness and vigilance of earlier Post-punk.

In the late 1980s and the 1990s, many Japanese groups morphed Rock unto their liking, integrating various influences. Ruins developed Brutal Prog using raw production and dense usage of dissonance and uncommon time signatures. Boredoms combined volatile rhythmic sections, often utilizing numerous drummers, with glitchy, psychedelic post-production, while Ground-Zero incorporated heavy sample usage, turntables, omnichords, and traditional Japanese instruments. During the 1990s, a loose movement known as Post-rock became the dominant form of Experimental Rock.

Though no particular movements emerged in the 2000s and 2010s, swaths of individual bands pushed the Experimental Rock. As of the 2010s, the term “Experimental Rock” has fallen to indiscriminate use, with many modern rock bands being categorized under prefixes such as “post-“, “kraut-“, “psych-“, “art-“, “prog-“, “avant-” and “noise-“.

sources: discogs, wikipedia, rateyourmusic