Auditory localization of nearby sources. II. Localization of a broadband source

Although many researchers have examined auditory localization for relativel y distant sound sources, Little is known about the spatial perception of ne arby sources. Ln the region within 1 m of a listener's head, defined as the "proximal region," the interaural level difference increases dramatically as the source approaches the head, while the interaural time delay is rough ly independent of distance. An experiment has been performed to evaluate pr oximal-region localization performance. An auditory point source was moved to a random position within 1 m of the subject's head, and the subject resp onded by pointing to the perceived location of the sound with an electromag netic position sensor. The overall angular error (17 degrees) was roughly c omparable to previously measured results in distal-region experiments; Azim uth error increased slightly as the sound source approached the head, but e levation performance was essentially independent of source distance. Distan ce localization performance was generally better than has been reported in distal-region experiments and was strongly dependent on azimuth, with the s timulus-response correlation ranging from 0.85 to the side of the head to l ess than 0.4 in the median plane. The results suggest that the enlarged bin aural difference cues found in the head-related transfer function (HRTF) fo r nearby sources are important to auditory distance perception in the proxi mal region. (C) 1999 Acoustical Society of America. [S0001-4966(99)04310-6] .