Mitigation of binaural front-back confusions by body motion in audio augmented reality

Front-back confusions are a well-known phenomenon of spatial hearing whereby the listener incorrectly localizes a source to its mirror image position across the frontal plane. This type of localization error can occur for real and synthetically spatialised sound sources. Experiments have shown the listener can resolve front-back ambiguities by rotating their head; also that sound source movement can resolve confusions if the listener is aware of the intended direction of source movement. The present outdoors experiment studies the mitigation of front-back confusions for synthetic binaural spatial audio interactive with body movement but not head-turns. This partly disabled mobile augmented reality system renders sound source positions relative to the world reference frame, (so the listener may walk past a stationary spatialised sound), but it renders instantaneous source bearing relative to the listener’s reference frame. Experiment participants walked past synthetic binaural sound sources with initial azimuths of ±(40°, 60°, 80°, 100°, 120 ° and 140°) and initial distance of 20 metres. Walk distances were chosen to result in azimuth changes of 4°, 8°, 12 ° and 16° between initial and final source bearings. Each factor combination resulted in a corresponding source distance change over the course of the walk. Front or back judgments of the initial source positions were recorded before and after walking. Results show statistically significant improvement of front-back localization for source azimuth changes of 12 ° or 16°, and source distance changes of at least 0.21 of the initial distance. [Keywords: front-back localization, binaural, mobile audio augmented reality] 1