In computer accompaniment, a computer music system listens to a live performance and synchronizes an existing accompaniment. You can read papers about computer accompaniment work at Carnegie Mellon. Roger Dannenberg's patent on computer accompaniment is licensed to MakeMusic!, which was formed to commercialize computer accompaniment as educational software. The resulting [broken link: http://www.makemusic.com/practice_tools.asp] SmartMusic system is used by over 30,000 students (as of September, 2004).