Spatial Sound in a 3D Virtual Environment: All Bark and No Bite?

Although the focus of Virtual Reality (VR) lies predominantly on the visual world, acoustic components enhance the functionality of a 3D environment. To study the interaction between visual and auditory modalities in a 3D environment, we investigated the effect of auditory cues on visual searches in 3D virtual environments with both visual and auditory noise. In an experiment, we asked participants to detect visual targets in a 360 degrees video in conditions with and without environmental noise. Auditory cues indicating the target location were either absent or one of simple stereo or binaural audio, both of which assisted sound localization. To investigate the efficacy of these cues in distracting environments, we measured participant performance using a VR headset with an eye tracker. We found that the binaural cue outperformed both stereo and no auditory cues in terms of target detection irrespective of the environmental noise. We used two eye movement measures and two physiological measures to evaluate task dynamics and mental effort. We found that the absence of a cue increased target search duration and target search path, measured as time to fixation and gaze trajectory lengths, respectively. Our physiological measures of blink rate and pupil size showed no difference between the different stadium and cue conditions. Overall, our study provides evidence for the utility of binaural audio in a realistic, noisy and virtual environment for performing a target detection task, which is a crucial part of everyday behaviour-finding someone in a crowd.