Filmmakers can include spoken words, sound effects, music and silence in the soundtrack. Each may be used in the usual manner, but each may also be used in surprising ways.
Dialogue is usually dominant and intellectual, music is usually supportive and emotional, sound effects are usually information. Their uses however, are not inflexible. Sometimes, dialogue is non-intellectual and aesthetic, sometimes music is symbolic, and on occasion sound effects may serve any of these functions. Any of these elements may be dominant or recessive according to the sharpness or softness of the sound and the relationship of the sound to the image.
(Murch, "Sound Designer", 298)
Possible Soundtrack Components
- Dialogues and monologues, including vocals that convey meaning. For example, "hmmm" = "I dont know", "Let me think about that", or some other meaning depending on context.
- Narration = spoken comments on subjects on screen or off.
- Sounds made by objects. Example: a falling tree crashing into an asphalt pavement.
- Sounds made by people (other than spoken words). Example: a person walking on gravel.
- Ambient sound = typically, usually unnoticed sounds of a place. Examples: the wind blowing through bckyard bushes, indistinct conversations at a party.
- Instrumental sounds
- Non-electronic materials. Examples: wood, plastic, glass, a combination of materials.
- Electronic and non-electronic combinations. Example: selective use of the Theremin and elsewhere orchestral music in The Day and Earth Stood Still (1951)
- Vocals. Examples: singing, chanting, humming, rhythmic grunting, rhythmic forced laughing, whistling, yodeling, the throat singing heard in the documentary Ghengis Blues (1999).
- Instrumental sounds and vocal combinations.
No Sound. Example: an astronaut tumbling lifelessly through space in 2001: A Space Odyssey (1968)