Arbeitsgruppe Medizinische Phys., Fachbereich Phys., Carl von Ossietzky Univ., D-26111 Oldenburg, Germany
The human binaural hearing provides a precise internal image of external sound source locations. Although the determination of the azimuthal position of a sound source is primarily based on the evaluation of interaural time and intensity differences, the psychoacoustic processing of these cues to form an ``auditory spatial image'' is yet unclear. Especially for all angles of incidence on the ``cone of confusion,'' interaural differences are equal and therefore provide an ambiguous representation of the source location. However, neurophysiological studies with barn owls show that by integration of directional information across frequency bands an unambiguous internal representation of sound source locations can be obtained. These findings form a model of binaural localization which was adapted to the system characteristics and psychoacoustic parameters of human hearing. The model was implemented in real-time on a multiprocessor setup. First results with the localization of sounds under anechoic and normal room conditions indicate that incidence directions from ahead, above and from the back can be distinguished. A possible use of a preprocessing stage in a directional hearing aid is discussed.