Film voiceovers
Voiceovers can be used in film in a variety of ways, the most obvious being in the creation of animation and cartoons. These are often done with several voice over artists recording in the same studio to create seamless dialogues between characters.
Next, voice-overs are used for narration. Many films use the voice of a narrator over scenes to explain the story. These storytellers are often characters from the film, involved in the plot in some way, but occasionally the narrator will remain an anonymous, faceless voice.
Lastly, voice overs are used to dub foreign language films and 'spoof' films. This requires expert co-ordination to ensure the words and the on-screen movements match.
TV/Television voice-overs
For television, voice overs are used in the same way as film (for cartoons and animation, narration and dubbing) as well as more. Shorter programmes and projects allow for a broader range of uses: telecaster announcements, talk and quiz show introductions, advertisements, audio descriptions for the blind and partially sighted and news reports.
Radio voice overs
The radio projects requiring voice-over recording are much the same as TV. Without the visuals, the projects are denser with information and may require the inclusion of other sounds. Pre-recorded radio shows, comedy and drama shows, news reports, radio adverts and literary readings may require additional sound effects other specialist sound control.
--
Although the locations listed above would have equipment capable for the job, recording voice overs in a specialist recording studio instead of on location allows for better control over the sound produced. Sound booths would block out interference to create a clear sound without distraction.
Hertfordshire Recording Studio Blog
An Introduction to Voice Over Recording