This document discusses different types of audio codes used in films including dialogue, music, and sound effects. It describes diegetic sounds that are part of the film's world and non-diegetic sounds edited in later. Diegetic sounds are further broken down into on-screen sounds whose source can be seen, off-screen sounds coming from outside the frame, and sounds that move the narrative forward. Non-diegetic sounds include background music, voice-overs, and computer generated or Foley studio sound effects. Parallel sounds mirror the mood of a scene while contrapuntal sounds create discomfort by not fitting the scene.