I noticed something interesting several years ago when I was trying to identify some of the Mexican music tunes in “Treasure of the Sierra Madre”. After some practice, I was able to mentally tune out the loud dialogue of the film and concentrate on the background singing. Now I can do either, tune out the music and listen to the dialogue, or tune out the dialogue and listen to the music. But I have trouble now listening to both the dialogue and the background music at the same time, as I originally heard them together the first dozen or so times I saw the film.