What are the three basic categories of sound in film, and how does sound affect mood in film?
The three categories of sound in film are dialogue and narration, music, and sound effects.
Dialogue and Narration in film: This includes the emotionality of the spoken sounds, the subtext of the words, the connotation and denotation of words, the literal meaning and implied meaning of speeches, and rhetorical devices like symbolism and verbal irony; the Ocean's films are great for verbal irony as is The Cutting Edge (1992, Glaser).
Music in film: This includes the qualities of the music, like major or minor key, tempo, orchestration (wood winds, string, or brass, etc) and lyrics. Lyrics can enhance narration or dialogue; this is a point made in Music and Lyrics (2007, Lawrence).
Sound Effects in film: These are the added sounds that illustrate or complement the action of the film, Equally, sound effects might carry symbolic meaning. like a knock on a door symbolically representing opportunity knocking, like in Don't Go Breaking My Heart (1999, Patterson).
Sound in film affects mood in a variety of ways. Sound effects and music may increase the mood of tension or suspense, like in Jaws (1975, Spielberg) or Sleepless in Seattle (1993, Ephron). Music is often used in romances to heighten the perception of affection and intimacy, like Message in a Bottle (1999, Mandoki). Dialogue of course, creates mood through tone and emotionality as well as through content, like in Holiday (2006, Meyers). In addition, voice-overs might add a mood of mystery or contemplation as in Shall We Dance (2004, Cheslom).
In summary, sound can affect mood in film in any way a director wishes it to: there are no limits to how mood and sound interact. Even silence, the absence of sound, heightens the established mood of a scene or film, as in Moneyball (2011, Miller).