Ambient Noise, Room Tone
(engl.: room noise, room Sound, room tone, wild sound) Atmospheric sounds in film, Atmo for short, provides environmental realism (Exterior - Forest, Country Road, etc. / Interior - Hallway, Room, Cave, etc.) or natural sounds (Rain, Wind, Birds, Machinery, etc.) as well as the social framework of an event (Children Laughing, Soccer Fans or similar) Snatches of background conversations must not divert attention from the actor's dialogue.
Atmosphere is usually recorded with the Direct Sound (Production Sound Recording), but can also be applied during post-production sound editing.
Room Tone is collected to provide audio continuity. Dead silence would be perceived by the film viewer as a failure of the audio track and would disturb the viewers suspension of disbelief.