Sound Mixing

The combination, during the phase of postproduction, of three different categories of film sound-dialogue, sound effects, and music. This can be done in either the original shooting process or in editing. Two or more sound sources can be connected to a sound mixer. For example at 0.12. I think it was used to here to create the scene and make it more real life like, as it is in a public place different background noises would be heard as well as the characters speaking to each other.