There are different types of sound during TV and film:
Diegetic: Natural sounds that are sourced within a scene, such as the people talking, or noise made by movements, doors opening and the radio or television in the background. The main types of TV pregrammes that use these are soaps such as Eastenders and Coronation Street or medical dramas such as Holby City, as they want the scenes to appear like everyday life and to make them more credible.
Non-Diegetic: Sound that is added to a scene to create an atmoshere, such as a soundtrack. A potential problem would be that it loses realism, but it does create a dramatic effect.
Sound Bridge: Sound which carries on over two different scenes which then literally creates a bridge between two events.
Incidental Music: Small, very brief snippets of sound which creates an emotion or feeling. This is normally more cultural, than for a character.
Asynchronous Sound: A natural sound, which is out of place and without a source on the scene.
Contrapunctual Sound: Sounds which create opposite emotion to the one which is on screen.