Combined assessment of auditory distance perception and externalization

This study investigates frontal auditory distance perception (ADP) and externalization in virtual audio-visual environments, considering effects of headphone rendering method, room size, reverberation, and visual representation of the room. Either head-related impulse responses from an artificial head or a spherical head model were used for diotic (monophonic) and binaural auralizations with and without real-time head tracking. The visuals were presented through a head-mounted display. Two differently sized rooms as well as an infinitely extending space (echoic and anechoic) were used in which an invisible frontal virtual sound source was located. Additionally, the effect of a freely movable loudspeaker for visually indicating perceived distances was investigated. Both ADP and externalization were significantly affected by room size, but otherwise the two perceptual quantities differed in their outcomes. Room visibility significantly affected ADP, leading to considerable overestimations and more variability in the absence of a visual environment, although externalization was not affected. The movable loudspeaker improved distance estimation significantly, however, did not affect externalization. For reverberation, a (non-significant) trend of improved ADP was observed, however, externalization was significantly improved. Different headphone renderings did not significantly affect ADP or externalization, although a clear trend was observed for externalization.