Observations: Ryuichi Sakamoto's unchained melodies

"I am just trying to avoid being a slave to the old musical system," says Ryuichi Sakamoto of his new CD, Out of Noise. "I was doing that when I was 18, but then came a long detour into pop and film music. I now want to get back to my roots." And the world's most eccentric singer-songwriter gives a self-deprecating laugh: that detour included modelling for Gap, playing a sadistic prison guard opposite David Bowie, co-starring with Madonna in the video for Rain, and composing the music for a long list of feature films, including Shirin Neshat's 2009 Women Without Men.

This new urge has led to a wonderfully beguiling record, sometimes reminiscent of Arvo Pärt, sometimes medieval-modal, and sometimes – with the sampled sound of rain and wind in leaves – quintessentially Japanese. "I wanted to make music from random noise – to grab melody and harmony from it – but I want there to be no demarcating line between what I find, and what I make from it." But behind this lies a philosophical gesture. "Almost everything that can be composed, has been composed," he says. "There is only a very small space in which composers can write new melodies." Where is that space? "Using computers, we can use frequencies and time as a canvas. Like a painter or sculptor, we can put a sound object wherever we want on this canvas."

Next week he's starting a UK tour, performing music from Out of Noise, and also from his new film-score CD, Playing the Piano.

Ryuichi Sakamoto performs at the Birmingham Symphony Hall on Sunday (www.thsh.co.uk), and thereafter in Manchester, Brighton and London.