Definition of "non-diegetic" [non-diegetic]

• That does not occur as part of the action, and cannot be heard by the film's characters; background (adjective)

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• "The blurring of the lines between diegetic and non-diegetic sound and music in Halo 2 is a powerful technique that, in my mind, makes the sonic material all the more powerful."
• "I had to look up "non-diegetic", um, and "orchestra" and "musical", plus a lot of other words, but it was worth it."
• "Rivette accompanies these scenes of potentiality with the film's only non-diegetic sound, a selection of stunning pieces by the Bulgarian women's choir compilation Le Mystère des Voix Bulgares, music of such unearthly beauty that it is nearly alien, music that seems to emanate from and yearn for a world far beyond the corporeal plane."