Having recently seen the first trilogy among Nolan's works, I wonder what opinions you hold about the movies in general. Seeing that I'm quite late to the party, I expect some strong and mature takes in the comments, but you are still free to voice any opinion you may have.
I think I know what you mean. And it's funny you say "hum", because that kind of describes the soundtrack. It's mostly quietly, slowly moving deep string harmonies, sort of like a hum, so it's totally understandable that nothing of it really stands out. I think it's mostly for creating atmosphere.