Steve Reich: Clapping Music

A rhythmically very interesting composition is Clapping Music by Steve Reich. It is based on a rhythmic motiv, which is repeatedly clapped by two players. One player repeats the motiv as given, while the other player claps a iteratively shifted version of the motiv. At each shift, the motiv is displaced by one eighth note to the left, wherupon the rhythm is wrapped. A corresponding score is shown below:

 

The score, however, does not explicitly specify the idea of the iterative rhythmic displacement. In an MPS context tree model, the rhythmic modification process can explicitly be described using appropriate control structures:

In the language, this can be written as follows:

title "Clapping Music"
composer "Steve Reich"

composition
{
    time 12/8, tempo 168
    {
        instrument handClaps
        {
            parallel
            {
                repeat 13
                {
                    fragmentRef motiv
                }
                for n in 0 to -12 step -1
                {
                    fragmentRef motiv
                    {
                        rhythmicDisplacement mode wrap offset n/8
                    }
                }
            }
        }
    }
}

fragment motiv
{
    repeat 4
    {
        rhythm 8 8 8 _8 8 8 _8 8 _8 8 8 _8
    }
}

The source code and the corresponding representations shown in this example are also available in the github example repository.