Have just stumbled across this article from the New York Time in January.
It is a discusison of the use of sound and music (or lack of it) in the Coen Brothers' "No Country for Old Men". If you've not seen it, go watch it now!!
Some of the most intersting quotes from the article:
"By compelling audiences to listen more closely, this unnervingly quiet movie has had the effect of calling attention to an underappreciated aspect of filmmaking: the use of sound."
"Suspense thrillers in Hollywood are traditionally done almost entirely with music,” he said. “The idea here was to remove the safety net that lets the audience feel like they know what’s going to happen. I think it makes the movie much more suspenseful. You’re not guided by the score and so you lose that comfort zone.”"
"“The essence of sound design is you can’t record the sound,” Mr. Lievsay said. “You have to take a lot of sounds and put them together.""