Influence of the ventriloquism effect on minimum audible angles assessed with wave field synthesis and intensity panning

The psychophysical phenomenon called ventriloquism effect describes a possibly occurring influence of a visual stimulus on the judgment of a sound source’s perceived position. The term minimum audible angle usually denotes the just distinguishable horizontal angular deviation between two sound sources. It depends on the direction of the sound sources relative to the listener’s head, the considered sound stimuli, and the presentation sequence. Within this paper, a possible influence of the ventriloquism effect on the minimum audible angle for sequentially presented broadband noise is assessed with wave field synthesis and intensity panning as reproduction methods in a reflective environment, using an adaptive two-alternative forced choice procedure. As baseline, the minimum audible angle without any intended visual stimuli is determined in complete darkness for both reproduction methods. These baseline data are compared to absolute localization trial results for validation purposes. As visual stimuli, one concurrent and one contradictory light spot are added to the sound stimuli. A possibly occurring ventriloquism effect can reduce or enlarge the minimum audible angle depending on whether the visual stimulus’ position change is larger or smaller than the change in sound source position. It is shown that visual stimuli can influence minimum audible angles for both reproduction methods, at which considerable differences occur inter-individually and between the considered reproduction methods.