Tuning in

 "Tuning In – a film about Karlheinz Stockhausen" was produced by Barrie Gavin for the BBC's "Horizon" serie in 1981. Directed by Robin Maconie - who wrote a lot of articles around the work of  Karlheinz Stockhausen - this documentary is an informative introduction to the work and process of a man who shook music and consciousness up.
The film shows Stockhausen instructing a group of professional musicians to start playing only at the moment when their minds were absolutely clear. 

"New methods change the experience, and new experiences change man. Whenever we hear sounds, we are changed, we are no longer the same, and this is more the case when we hear organized sounds; music.” Karlheinz Stockhausen