Diegetic

Sound is called diegetic when its source is visible or implied in the world of the film. Common diegetic sounds present in most films are:

actors speaking to each other (dialogue)

sounds originating from any object on the screen, like footsteps and police sirens

music that comes from a sound system or orchestra Diegetic [di-a-JE-tic] comes from the greek word diegesis and it means to recount a story. Diegetic is also known as actual or literal sound.

Diegetic sounds can further be categorized as source-connected or source-disconnected depending on whether the sound source is visible or implied on the screen. A visible source is shown on the screen, while an implied source is still part of the film world but not shown on the screen.

Non-Diegetic

Sound is said to be nondiegetic when its source is not present or implied in the narrative universe. Common instances are:

music or score, used to augment emotions

actor’s commentary or narration

any extra sound added for effect

Non-diegetic is also known as commentary or nonliteral sound.

Below is an extra credit video assignment I did with a couple friends. It’s about sound in a broader sense, but at 3:27, we discuss and exemplify the difference between diegetic and non-diegetic sound: