diagetic vs. mimetic

"Music is used in two modes within films: diagetic and non-diagetic. Diagetic music is music which occurs within the narrative of the film. It is attributable to some source seen in the film, such as a radio, a record player, a musical instrument, a juke box or an orchestra in a concert hall. The characters of the film can hear this music. Non-diagetic music is music which is not part of the narrative, not attributable to a source in the film, and is unheard by characters in the film. This type of music is usually used to add affective colour to the film, and play on the emotions of the audience. It can be used to cue the audiences to feel uneasy; to build up tension; to flag an approaching disaster or to signal a love affair. Some composers, such as Korngold (composer of the music for the 1940 film ``Sea Hawk'') associated particular characters with a non-diagetic musical theme, in the leitmotivic style (see below) most commonly attributed to Wagnerian Opera. This type of music is, for the most part, used to cue events in the narrative, although non-diagetic music playing at a counterpoint to the narrative can achieve interesting results. "

Diagetic/Non-Diagetic: The word ?diagetic? simply refers to whether an aspect of the film itself is motivated by something in the film?s plot or setting (diagetic) or is part of the filmmaking process (non-diagetic). This term usually applies to sound and lighting, but it can have other applications as well. For example: Candle-light is notoriously weak and almost impossible to film by (although it has been done on several occasions). How-ever, whenever we see a scene in a film with lots of lit candles, the lighting is usually soft and warm, much like the light of a candle. The lights used to light the scene are almost certainly special filmmaking lights, not just the candles, but they are configured in such a way as to resemble candle-light. This is diagetic lighting. Sound works in the same way. The easiest example of non-diagetic sound is the film?s soundtrack. Whenever you hear spooky theremin music in an old science fiction movie, chances are good there isn?t somebody standing on-screen playing a theremin, and as such the music is non-diagetic. However, at the ball scenes in Snow White: A Tale of Ter-ror we hear Claudia singing and hear the band playing, both of which are portrayed on-screen. This is diagetic sound, as it has a source on-screen. Smart filmmakers (especially horror filmmakers!) use, and often blur, the lines between diagetic/non-diagetic lighting and sound to heighten suspense and atmosphere. The most classic example is the shower scene in Psycho. Herrmann?s score of shrieking stringed instruments is definitely non-diagetic, but it is executed so perfectly it seems almost as if the music is created by Norman Bates?s knife and, as such, it adds a great deal of impact to the scene. If you doubt this, watch the scene muted sometime and see if it feels at all the same.

Viewing Guide for Snow White: A Tale of Terror 2 the same! Lighting can work in the same way. For example, the heroine is being stalked by some unknown horror through a dimly lit house in a thunderstorm. The only glimpse of the stalker we see is when lightning strikes outside and the room is momentarily illu-minated. Unlike Herrmann?s score, the lighting in this case is diagetic, but it is still ma-nipulated to serve the same purpose.

mimetic - American Heritage Dictionary

... Relating to, characteristic of, or exhibiting mimicry. * a. Of or relating to an imitation; imitative. b. Using imitative means of representation: a mimetic dance. [Greek m m tikos, from m m sis, mimicry ; see mimesis.] mi·met i·cal·ly adv. The American Heritage ® Dictionary of the English Language ...
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Hope that helps!