Chicago witnessed the birth of Acid House in 1987 with the release of Phuture's Acid Tracks E.P. Created accidentally by Phuture DJs and musicians during a test session with a Roland TB 303 bass machine, Acid House's squiggly bass sound is a mind-warping, compelling hook. Acid effects emitted from the machine swirl, stab, and spiral uncontrollably across House's four/four beat. The mix has a sour sensation that is difficult to follow and virtually impossible to recreate. The term "acid" was utilized to describe the new sound for the peculiar, hallucinogenic effect it had in the clubs and for its kinship to Acid Rock. With its lack of sampling, Acid House tapped into a different kind of emotion than its famously sample-heavy predecessor known as House. Rather than developing a mature, soulful sound, Chicago-based Acid House satisfied a craving for all-night dancing euphoria worldwide. After spending a summer spinning to Acid House tracks in the open-air clubs of Ibiza, Spain, DJs Paul Oakenfold, Danny Rampling, Johnny Walker, and Nicky Holloway returned to the U.K., bringing the pleasure-principled "Balearic" sound to London's clubs. England quickly transformed Acid House into rave culture, while many of Acid House's architects brought the sounds even further, creating new and emerging forms.