Mental spatialization; the psychological process (in monaural film viewing) of locating a sound's source in the space of the image, no matter what the real point of origin of the sound in the viewing space is, e.g. one will mentally place a voice as coming from offscreen left, in tandem with visual indications about the person speaking, even though the sound really emanates from a speaker behind the centre of the screen.
(Source - Chion, Michel. (1994) Audio-Vision: Sound on Screen. (Trans. Claudia Gorbman) Columbia University Press.)