Spatial imaging is commonly thought of by the composer in relatively objective way as a means of enhancing the sounding properties inherent in spectro-morphologies and structural relations. Simply stated, a musical gesture can be more vividly dramatised through spatial displacement, just as a texture can be made 'environmental' through spatial distribution. Such spatial imaging, considered by the composer and composed into the music, I shall call composed space.
The (indoors) listening space encloses and may either confine or expand the composed space. This ultimate space where the listener perceives is therefore a superimposed space, a nesting of the composed spaces within a listening space. (Source - Denis Smalley (1991). L'espace du Son II. Ohain: Editions Musiques et Recherches.)