Sound Terminology

The audio portion of a film including dialogue, music, and effects. Sound effects refer to all created sounds except dialogue or music.

Asynchronous

The audio-track sounds that are mismatched or out of sync with the images on the screen, sometimes accidental, but sometimes intentional.

Background music

The part of the score that accompanies a scene or action in a film, usually to establish a specific mood or enhance the emotion.

Dialogue

Any spoken lines in a film by an actor/actress.

Direct sound

The technique of recording sound simultaneously with the image.

Lip sync

The to synchronization between mouth movement and the words on the film's soundtrack.

Monologue

A scene or a portion of a script where an actor gives a lengthy, unbroken speech without interruption by another character.

Film score

The background music component of a movie's soundtrack, usually composed specifically for the film by a film composer.

Soundtrack

Technically, this term refers to all the audio components of a film, including the dialogue, musical score, narration, and sound effects.

Synchronous sound

Refers to the sound that’s source can be seen in the frame, or whose source can be understood from the context of the image.

Theme music

The opening or closing music of a motion picture, often containing the film's 'signature' or leitmotif tune/phrase that is associated with a character or situation within the film.

Voice-over (or V.O.)

Refers to recorded dialogue, usually narration that comes from an unseen, off-screen voice, character or narrator that can be heard by the audience but not by the film characters. A technique in used Film Noir.

Reference: www.filmsite.org