Sound Glossary

Non-diegetic sound - Sound whose source is neither visible on the screen nor has been implied to be present in the action:

• Narrator's commetry
• Sound effects which is added for the dramatic effect
• Mood music

Diegetic sound - Sound whose source is visible on the screen or whose source is implied to be present in the action:

• Voices of characters
• sounds made by the objects in the story
• Music represented to be comeing from the instruments in the story

Soundtrack - A soundtrack can be recorded music accompanying and synchronized to the images of a motion picture, book, television program or video game

http://en.wikipedia.org/wiki/Soundtrack

Theme tune - Theme music is a piece that is often written specifically for a radio program, television program, video game or movie, and usually played during the title sequence and/or end credits

http://en.wikipedia.org/wiki/Theme_music

Incidental music - Music composed to accompany the action or dialogue of a drama or to fill intervals between scenes or acts

http://www.thefreedictionary.com/dialogue

Sound effects (FX) - An imitative sound, as of thunder or an explosion, produced artificially for theatrical purposes, as for a film, play, or radio programme

http://www.thefreedictionary.com/sound+effect

Ambient sound - Ambient sound or ambient audio means the background sounds which are present in a scene or location

Dialogue - Conversation between characters in a drama or narrative

http://www.thefreedictionary.com/dialogue

Voice-over - The voice of an unseen narrator, or of an onscreen character not seen speaking, in a movie or a television broadcast

http://www.thefreedictionary.com/dialogue