Jonny Greenwood on BBC Radio 3

Robert Sandall asks Jonny Greenwood about white noise for BBC Radio 3's interval feature, on the night the BBC Concert Orchestra plays Popcorn Superhet Receiver, his first commission as their resident composer. To Greenwood it is an output on the synthesisers, “the hiss with which you build lots of other things”, and it is in the air conditioning, the hard drive and the fridge. On stage Radiohead often play a radio, picking up the local languages and music of whatever city they are in, or just the howl and hiss of noise when there is no reception. They once built software that recorded a few seconds of shortwave at a time over 24 hours.

His feel for white noise goes back to family car trips with three or four cassettes, the same ones every time: a cheap English imitation of Simon and Garfunkel, a Mozart horn concerto and Flower Drum Song. He heard them so often that even when they weren't playing he could hear the songs in the engine noise, every detail, passing in his mind in real time. Music is easier to recall in that detail, he says, with noise in the background; in a silent room he could never follow a song through in real time like that. He managed four weeks of a music degree at Oxford Brookes before Radiohead signed to EMI, and one lecture, on Penderecki's piece for the victims of Hiroshima, stuck with him, the idea that strings alone could make white noise.

One idea for the commission was to turn the orchestra into a drum machine, with violins for hi-hat and snare, and all it produced was a very loud atonal chord over and over. “I'm very bad at writing any sort of silence,” he says. A pause in a score makes him feel awkward, “a bit like social embarrassment”.