Voiceovers: offscreen, offstage or otherwise unseen narrations, announcements or vocal utterances — voice — usually (but not necessarily) heard over visual images.
These are all examples of voice overs:
- radio and TV station identifications,
- documentary narrations,
- voicemail greetings,
- web voice-assist prompts,
- corporate video narrations,
- training narrations,
- radio commercials,
- off-camera television commercials,
- medical narrations,
- audiobook narrations,
- Mary Alice Young‘s insights on Desperate Housewives, and
- the most famous line in Citizen Kane (because it was added to the scene with enhanced sound effects in post-production — after the scene was shot).
The term voice over originally came from the film industry. It was the term used to designate on the movie script the off-camera voice heard over the onscreen action.