On "This American Life," a show produced by Ira Glass on National Public Radio, there was a piece about a guy who figured out the pitch of all the little hums in his background -- computer fans, a/c, etc. He took a list compiled by some musicologist (maybe; memory is foggy on this point) that ascribed some emotion to various intervals, and figured out what emotional moods his background noises might be producing in him. It was an interesting idea, that vague feelings of anxiety, for example, might be due to the pitch relationship between his computer and the ventiliation system at work.