Whilst GruntCount is thought of as an improvisation by its performers and the composer, it is also to some extent a repeatable and rehears-able piece of music. Notation instructions have been replaced by a pre-defined structure that is learned as the player prepares for a concert. However, the duration of the piece and the sounds the instrumentalist will play are largely open and the piece can be configured to last anywhere between 5 and 20 minutes depending upon the needs of the performance. Such extremes are possible (and permissible), because this is part of the fundamental concept of the piece. Not only should this piece of computer music be accessible and reliable enough for players to be able to rehearse alone, the player is granted autonomy to change the scope and scale of the piece by changing the number of ”grunts” to count before the piece finishes. A player who has rehearsed the piece several times will develop an understanding of how the musical tension develops and this will give the player confidence to find musical solutions to some of the unexpected events the computer may throw up as the piece runs.