Representation is used here in the sense of sound material that primarily evokes non-sounding qualities - both physical and psychological - rather than being involved with sensory inputs associated directly with an object.
See also:Abstract Sound, Anecdotal Composition, Diapositive Sonore (Sound Slide), Mimesis, Phonography, Re-presentation, Referential Sound
Bibliography: Couprie, Pierre (2001b). Transcription globale : introduction à la représentation
Waters, Simon (1994). Timbre Composition: Ideology, Metaphor and Social Process