Film sound is carefully designed and added during post-production to emphasize important elements and set the atmosphere. There are different types of sounds that can be used including selective sounds to highlight key audio, ambient sounds to establish setting, and sound bridges to smoothly transition between scenes. Sound can be either diegetic, existing within the film's world, or non-diegetic coming from outside the story like music or narration. Proper use of synchronous, asynchronous, and contrapuntal sounds further enhance the visuals and create meaning.