Simply known as just "acid" is a sub-genre of house music developed around the mid-1980s by DJs from Chicago. The style is defined primarily by the "squelching" sounds and basslines of the Roland TB-303 electronic bass synthesizer-sequencer. The influence of acid house can be heard on later styles of dance music. This new collection combines house music's ubiquitous 4/4 beat melodies with the electronic sound produced by the Roland TB-303 electronic synthesizer-sequencer by constantly modulating its frequency and resonance controls to create movement in otherwise simple bass patterns.