Virtual auditory aperture passability.

Two experiments investigated (1) the ability of individuals to perceive the passability of apertures that are constructed using two virtual sounds sources and (2) the nature of the perceptual information that is used when determining passability in such a way. In the first experiment, participants judged whether they could successfully walk between two sound sources, heard through headphones, without turning their shoulders. We hypothesized that judgements would be accurate and driven by the detection of a proposed informational variable that relates head rotation, forward locomotion and aperture width. To test this hypothesis, we used motion tracking and a gain manipulation to alter apparent head rotation relative to virtual sound source positions and evaluated the effect on performance. Participants were able to accurately judge aperture passability based only on acoustic information. However, the gain manipulation did not show a significant influence on perceptual reports. The unexpected significant influence of lateral head movement on perceptual accuracy, however, does suggest that an alternative informational variable, based on lateral movement, may have been used. In the second experiment, a group of participants with wide shoulders was compared to a group with narrow shoulders on a similar task. Significant differences in minimally acceptable aperture width were found between the wide and narrow groups. When these aperture widths were scaled to the participants' shoulder widths, however, the differences were no longer present. These findings are consistent with previous studies investigating perception of passability and offer promising applications of virtual reality technology in the study of auditory perceptual abilities.