The perception of the position of a sound source in space. Sounds below about 1,000 hertz (about two octaves above Middle C) are located in the horizontal plane by momentary binaural time differences called transient disparity and phase delay, and high-pitched sounds are located through binaural intensity differences called sonic shadows. Humans have a minimum audible angle in the horizontal plane of about 2 degrees, but like other terrestrial animals are not good at locating sound in the vertical dimension, whereas the barn owl, which hunts fieldmice and other prey in total darkness, can locate sound sources to within about one degree in both the horizontal and vertical dimensions (azimuth and elevation), more accurately than any other species that has been tested, its left ear pointing downwards and its right ear upwards to aid localization in the vertical dimension. Also called auditory localization or auditory space perception. See also audiogravic illusion, auditory receptive field, biosonar, cone of confusion, pseudophone, superior olivary nucleus, trapezoid body.