voice over

/vɔɪs ˌoʊvər/

Voice over is a kind of narration that's used in a movie or TV show. The voice over in a documentary might tell the story of the Vietnam War, while photos and film clips illustrate it.

If you're watching a movie and there's a voice telling a story, but no footage of the person who's speaking to go along with it, that's a voice over. A voice over in theater is known as "off stage commentary," while in film it's also called "off camera commentary." This can take the form of narration by someone who appears onscreen in other parts of the program, or by someone who's hired only as a voice actor.

Definitions of voice over

1. noun

   the voice on an unseen commentator in a film or television program
   type of:

   phonation, vocalisation, vocalism, vocalization, voice, vox

   the sound made by the vibration of vocal folds modified by the resonance of the vocal tract