Acid House is a subgenre of house music that emerged in Chicago in the mid-1980s. It is characterized by the distinctive "squelching" sound produced by the Roland TB-303 bass synthesizer, achieved by manipulating the synthesizer's filter resonance and cutoff frequency while a sequence is playing.

Key features of Acid House include:

Use of the Roland TB-303 or similar synthesizers

Repetitive, hypnotic basslines

Minimalist structure with focus on rhythm and texture

Four-on-the-floor beat typical of house music

The genre originated when Chicago producers discovered unconventional ways to use the TB-303, originally designed as a bass accompaniment for guitarists. This experimentation led to the creation of the iconic acid sound.

Acid House gained significant popularity in the UK during the "Second Summer of Love" in 1988, catalyzing the rave culture and influencing the development of other electronic music genres. The movement was closely associated with the use of MDMA (ecstasy) and a distinctive fashion style featuring smiley face symbols.

Notable tracks include Phuture's "Acid Tracks" (1987), often cited as the first Acid House record. The genre's influence extended beyond music, impacting fashion, visual arts, and club culture.

Acid House's legacy continues to resonate in contemporary electronic music, with modern producers using both vintage equipment and software emulations to recreate and evolve the acid sound.