A novel improvisation‐oriented live performance situation is proposed. Its implementation is described, and results from actual performances are presented. This performance context involves a musician performing on an instrument outfitted with sensors which feed a computer system that monitors certain aspects of the instrument's behavior such as its pitch, loudness, and timbre. Another performer interacts with the system to selectively record, transform, and play electroacoustics materials derived from the instrumentalist's performance. This situation might be characterized as one involving an improvising soloist with an accompanist who constructs the accompaniment from phrases attentively trapped from the soloist's ongoing performance. The system requires a running or short‐term memory mechanism with procedures that aid in the parsing of selected phrases, a supple user interface for the accompanist that facilitates the selection and transformation of the musical materials as well as their expressive performance, and a rich set of procedures for producing variations. A number of successively refined implementations of this idea have been made, the most recent of which uses the MAX programming environment developed by Miller Puckette at IRCAM. The system provides for musical intimacy between the performers. It also provides the accompanist with an interesting set of tasks and the soloist with a stimulating accompaniment based on variations of his own materials.