Measurement of Auditory Alleys in a Virtual Environment and Their Mathematical Models

The use of a virtual environmental display system enabled the construction of a psychophysical experimental system to measure subjectively straight lines running phenomenally parallel to the median plane, the parallel alley, and subjectively straight lines running phenomenally equidistant from the median plane, the equidistance alley, in binaural auditory space. Experiments were conducted using the constructed experimental system, to measure the parallel alley and the equidistance alley in binaural auditory space. The following results were confirmed: (1) The parallel alley and the equidistance alley in auditory space in a virtual environment are not always straight in the physical sense, and their forms depend on the distance from the median plane. (2) The parallel alley lies inside the equidistance alley. These tendencies are the same as those between the parallel alley and the equidistance alley in visual space and/or tactile space in the real world. Moreover, by employing sound intensity and binaural time differences as parameters, space perception models were constructed to explain the parallel alley and the equidistance alley in auditory space. Based on the results of the simulation performed using the models, it was confirmed that the models successfully explain the results obtained in psychophysical experiments performed using the virtual environmental display system.