Africa Express Presents... Terry Riley's In C Mali

Process music is a movement in which a composition is generated by a clearly defined procedure or rule-set. Sometimes this procedure is made audible—so the listener can follow the gradual changes as they unfold—and sometimes the process remains hidden behind the surface of the sound. Typical processes include phasing (two identical patterns drifting out of sync), additive or subtractive procedures (expanding or contracting a pattern by fixed steps), iterative feedback (repeating an operation so the output becomes the next input), permutations, stochastic or probabilistic rules, or instruction-based performance systems. The aesthetic ranges from hypnotic and pulse-driven to fragile and static, but the core idea remains: the music arises from the process.

Minimalism is a style of Western art music that emerged in the United States during the 1960s, characterized by the use of very limited musical materials, steady pulse, and extensive repetition. Composers often build pieces from short cells or motifs that are repeated and slowly transformed through additive or subtractive processes, phase shifting, and gradual changes in harmony, texture, or register. Harmony is typically consonant (often modal or diatonic), though just intonation and extended drones are also common. The result is music that foregrounds process, clarity, audibility of structure, and a hypnotic sense of stasis and flow. Typical ensembles include keyboards, mallet percussion, strings, winds, voices, and electronics or tape. Minimalism influenced a wide array of later styles, from ambient and new age to post-minimalism and minimal techno.