Sound

Diegesis means the ‘world of film.’

Diegetic Sound: Sound that is part of the action is called diegetic sound and whose source is visible on the screen or whose source is implied to be present by the action of the film. If something seems to be part of the world of film, it is called diegetic (what we’d hear if it was in the film world.). eg. wind noise, screeching cars etc. They may also be added in after filming, or may be exaggerated for effect, eg. louder footsteps. The audience are aware that there are things taking place in the diegetic world around the edges of what we actually see on the screen.

Non-Diegetic Sound: It's not part of the film world and is added on. Sound whose source is neither visible on the screen nor has been implied to be present in the action. For example a narrator's commentary, sound effects which are added on for the dramatic effect, mood music etc.
Sound is often added to create mood or atmosphere.

Sound Bridge: This is when the sound from one scene continues into or over the next scene. The images we see change but the sound is still from the previous scenes. A film will be very disjointed if there were no sound bridges. They create a wider, more coherent diegetic world. Gives the film a sense of linking and joining together – part of a film’s continuity.

On Screen: You can hear it and see it at the same time.

Off Screen: You can't see it, but can hear it, often in a sound bridge. Sometimes used to give us clues as to what is going on around us that we cannot see.

The use of on screen and off screen diegetic sound helps to create the sense of our viewing a three dimensional world, rather than a flat screen.

Contrapuntal Sound: This is when we hear sound that doesn’t really match what we are seeing.

Parallel Sound: The music tone and mood matches the action on screen.

Foley Track: Sound effects track. Some sounds need to be made from scratch and others enhanced. Foley artists enhance and create sounds to be added after filming.