Free Improvisation differs from most other categories, as it's defined more by process than end result. Alternately termed "Free Music" or (for the technically minded) "Non-Idiomatic Improvisation," this broad heading encompasses spontaneously produced music that tends to sit on the fringes of and/or blur the boundaries between Free Jazz, Noise, Experimental Rock, and Avante Garde Classical. Free Improvisation first came into its own in the mid-1960s, as Europeans such as guitarist Derek Bailey and saxophonist Evan Parker began distancing themselves from their American Free Jazz influences, discarding blues-based sounds and drawing inspiration instead from the innovations of Karlheinz Stockhausen, John Cage, and Anton Webern. A whole generation of outsiders listened as noisemakers from Japan to New York took these early cues and expanded on them by mixing bizarre instrumental techniques with electronics, samples, and whatever else they could get their hands on. Free Improvisation continues to proliferate on an underground level, now counting the sine-wave and turntable explorations of Japan's Otomo Yoshihide as well as the outer-limits work of Swedish saxophonist Mats Gustafsson among its ranks.