Knock on Wood: Call and Response
Knock on Wood is a sound installation by composer Tom Johnson (Colorado, 1939) in collaboration with the artist Martin Riches (Berlin 1942). Composed of a collection of instruments, wooden blocks, scores and drawings, the proposal deploys various mechanisms treated mathematically in order to produce completely acoustic sounds. It is a work that synthesises the long and fruitful collaboration of more than thirty-four years between these two pioneers of experimental and minimalist music.
The installation uses ready-made wooden percussion instruments playing complex rhythms automatically that would be difficult to play accurately by hand. Each group of instruments is made from a different kind of wood, each with its own defining timbre. The installation consists of five different groups of instruments, each playing in a cycle ranging from approximately 20 minutes to one hour. Each group plays its own melody independently of the others followed by a silence.