The document introduces key concepts about sound in media. It divides sound into two categories: diegetic sound that comes from within the world of the film, like dialogue and ambient noise, and non-diegetic sound that does not have a visible on-screen source, like theme music. Sound helps create meaning by enhancing emotion, conveying character psychology, and setting location and period. Key terminology includes soundtrack, theme music, sound effects, ambient sound, dialogue, voiceover, sound bridges, parallel sound, and contrapuntal sound.