Ambience
The sounds of a spring day; birds chirping, children playing in a nearby park, bicycle spokes ticking as cyclists ride by. A bustling city street with its car horns, sirens, footsteps on pavement. These are examples of ambient sound. Ambient noise is essential for selling the idea of a particular environment. If the characters in a movie are supposed to be on a space ship or in a submarine and there is no deep, constant rumble in the background it’s going to sound like they are on a Hollywood film set instead of in that particular vessel. It can also be textural for underlying emotional content. Ambience can be a very subtle, yet effective tool in your arsenal. It is critical that whatever ambience sounds you use are appropriate. IE: if you are simulating a grocery store that has only a few customers then do not use recordings of crowded, bustling shopping markets. The minute your sounds are unconvincing, your audience will be lost.