Feature classification and related response in a real-time interactive music system
Robert C. Rowe · The Journal of the Acoustical Society of America · 1990
Cypher is a real-time interactive music system that has two halves: a listener and a player. The listener listens to and analyzes external musical input. The player uses various algorithmic techniques to produce new musical output. The two halves are each hierarchical, where higher levels correspond to longer spans of time. The listener classifies for the player features detected in the input and their behavior over time, and the player uses this information to produce music in response. Features characterized include speed, density, harmony, and duration. A graphic interface allows the user to specify relations between feature classifications and types of response. Collections of relations can be saved and recalled during performance by a score orientation section that tracks human performance and executes state changes at predetermined points in the score. Cypher plays composed music in a manner that is sensitive to live human performance cues. It is able to analyze and respond creatively to unknown music. Finally, it can compose without input, using algorithms to either transform remembered material, or generate new musical output.