Radiohead's fourth and fifth albums, "Kid A" (2000) and "Amnesiac" (2001)"," recorded simultaneously, marked a dramatic change in sound, incorporating influences from electronica, classical music, jazz and krautrock. Greenwood employed a modular synthesiser to build the drum machine rhythm of "Idioteque", and played ondes Martenot, an early synthesiser similar to a theremin, on several tracks. He composed a string arrangement for the track "How to Disappear Completely" by multitracking his ondes Martenot playing. According to longtime Radiohead producer Nigel Godrich, when the string players saw Greenwood's score "they all just sort of burst into giggles, because they couldn't do what he'd written, because it was impossible—or impossible for them, anyway". The orchestra leader John Lubbock encouraged the musicians to experiment and work with Greenwood's "naive" ideas.