Auditory localization: effects of reflecting surfaces

Based on anatomical and evolutionary conceptions of the human ear, an experiment was conducted in which forty-eight human subjects were asked to localize sounds (a human voice) emitted by one of twenty-seven stationary loudspeakers in an anechoic chamber. The position of the active loudspeaker varied with respect to azimuth, distance, and elevation in three steps each. The position of a single sound-reflecting surface (about 6 m2) was varied: on the floor, on the ceiling, to the left, and to the right. The accuracy of identifying the active loudspeaker for each position of the sound-reflecting surface was compared intraindividually with the absence of reflection. The results show an overall increase in correct localizations with a sound-reflecting surface on the floor. Especially the elevation of the sound source can be detected with greater precision. Additionally, the percentage of correct localizations decreased systematically with the presence of a sound-reflecting ceiling, while the presence of sound-reflecting walls did not systematically affect the localization performance. Judgments in the horizontal plane and those of distance were not systematically influenced by the presence of a sound-reflecting surface.