Diegesis is defined as the narrative construct a story takes place in, a world or universe with its own set of rules. Diegetic sound is sound that happens inside of this world, the characters are able to perceive it and it follows the rules of the world, ex. talking, footsteps, radio. Non-diegetic sound refers to sounds that happen outside of this world, ex. narrating or scores.
If the characters of a story can only hear diegetic sound and we want the audience to relate to the characters, it could be argued that we as sound designers should strive to use diegetic sound as much as possible. Using diegetic sound immerses the audience into the characters position. We face a problem if we want to do this in traditional cinema, a score is non-diegetic. How do we bring this non-diegetic emotional expression into the diegetic world?
This scene from Bird-man achieves this feat excellently. The drums start as non-diegetic, it’s a musical accompaniment outside of the story’s world. However by bringing the drummer into the world, the film maker has brought the audience and the characters together, we hear what they hear and so we understand to a deeper extent their perception of the scene, placing us in the story.
I think it would be very difficult to create a score that is completely diegetic, and so instead I’m going to create one that is shaped and informed by the diegetic world. It remains as non-diegetic but it has the quality of the diegetic sound.