Ambient Sound

This is usually background noise that is used to establish the location of the sound. For example, if a scene were in a park, sounds effects such as dogs barking and children laughing etc would be heard in the background of the main characters. An example is shown below at 0.30. This is used by the cheering nosies in the background highlighting it as a school play ground with a fight occuring but the girls chanting to the aggressive noises of the fight. I think it was used here to make the scene more realistic to the audience.