John Zorn's Cobra: Tokyo Operations '94

Conducted improvisation is a live-composition practice in which a conductor shapes collective improvisation in real time using a codified set of gestures, cue cards, and signals. Rather than pre-writing a fixed score, the conductor directs form, texture, dynamics, harmony, and orchestration on the spot, treating the ensemble as an instrument. Emerging from free jazz and experimental music, it bridges improvisers’ spontaneity with the clarity and contour of composed music. Systems such as Butch Morris’s Conduction, John Zorn’s game-piece approach (e.g., Cobra), and Walter Thompson’s Soundpainting offer different yet related languages for controlling entrances/exits, memory, repetition, density, and timbre. The result ranges from chamber-like transparency to big-band intensity, making conducted improvisation a flexible method used by jazz orchestras, experimental classical ensembles, and cross-genre collectives.

Indeterminacy is a strand of post‑war experimental music in which some aspects of a composition are left to chance or to the free choice of the performer, ensuring that no two realizations are exactly the same. The approach encompasses chance procedures used during composition (e.g., tossing coins or consulting the I Ching), open or mobile forms in which sections may be reordered, graphic or text‑based notation that prompts interpretation rather than strict reading, and time‑bracket techniques that specify durations but not exact synchrony. Closely associated with the New York School (John Cage, Earle Brown, Morton Feldman, Christian Wolff), indeterminacy challenged traditional authorship, fixed works, and score‑bound precision by shifting agency to processes and performers. While often conflated with “aleatoric” music, indeterminacy typically denotes unpredictability at the level of performance/realization (open form, variable notation), whereas chance composition may use randomness to create a fixed score. In practice, many works combine both.