You’re watching a movie. The scene is taking place outside a night club. We are in line watching and listing to a conversation between three people waiting to get in. We hear: cars going by, people laughing and shouting, the people in line are talking and the music from the club inside is muffled and low. Only the low end frequencies of the load pumping music are getting through the exterior wall. Every time the bouncer lets people in, the door opens and the sound waves run free, we hear the music more and more clearly as we get closer and close in line, until eventually we are let in and the sound of the music goes from a very low muffle, gradually into a very big, crisp, loud sound with a full dynamic range.
This is a technique we went over in studio using: A 4-band EQ, some simple reverb and some fades from the edited, low-end-freq music tracks to the original, crisper and louder music.
On a somewhat related topic (amazing sound editing and close attention to tone, and dynamics) check out the trailer for the excellent excellent film Pianomania, I saw recently at the Salem Film Fest: