Video example of Computer Accompaniment . In this video, the singer is accompanied by a computer. The notes and other score information was entered by hand from the score. The piano you hear is a MIDI synthesizer.
All processing is live and taking place in real time.
The computer listens to the soloist and classifies the performance according to style. The absolute meanings of these terms is not important. What is important is that the player and computer agree so that the computer can understand what the player intends. In the video, there is a transition from syncopated to frantic. I intentionally made the syncopation slightly more and more frantic until the computer decided to kick in with its own frantic response.