Effects of virtual speaker density and room reverberation on spatiotemporal thresholds of audio-visual motion coherence

• Published in: PloS one Vol. 9; no. 9; p. e108437
• Main Authors: Sankaran, Narayan, Leung, Johahn, Carlile, Simon
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 30.09.2014; Public Library of Science (PLoS)
• Subjects: Acoustic Stimulation; Acoustics; Adult; Audio equipment; Auditory Threshold - physiology; Biology and Life Sciences; Coherence; Cues; Ears & hearing; Female; Hearing - physiology; Humans; Intervals; Laboratories; Localization; Male; Medical research; Motion; Motion detection; Neurosciences; Noise; Pattern Recognition, Physiological - physiology; Pattern Recognition, Visual - physiology; Perceptions; Photic Stimulation; Quantitative psychology; Sensory integration; Signal processing; Sound; Sound Localization - physiology; Space Perception - physiology; Spatial data; Spatio-Temporal Analysis; Studies; Velocity; Vision, Ocular - physiology; Visual observation; Visual stimuli; Visual thresholds; Australia
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0108437

The present study examined the effects of spatial sound-source density and reverberation on the spatiotemporal window for audio-visual motion coherence. Three different acoustic stimuli were generated in Virtual Auditory Space: two acoustically "dry" stimuli via the measurement of anechoic head-related impulse responses recorded at either 1° or 5° spatial intervals (Experiment 1), and a reverberant stimulus rendered from binaural room impulse responses recorded at 5° intervals in situ in order to capture reverberant acoustics in addition to head-related cues (Experiment 2). A moving visual stimulus with invariant localization cues was generated by sequentially activating LED's along the same radial path as the virtual auditory motion. Stimuli were presented at 25°/s, 50°/s and 100°/s with a random spatial offset between audition and vision. In a 2AFC task, subjects made a judgment of the leading modality (auditory or visual). No significant differences were observed in the spatial threshold based on the point of subjective equivalence (PSE) or the slope of psychometric functions (β) across all three acoustic conditions. Additionally, both the PSE and β did not significantly differ across velocity, suggesting a fixed spatial window of audio-visual separation. Findings suggest that there was no loss in spatial information accompanying the reduction in spatial cues and reverberation levels tested, and establish a perceptual measure for assessing the veracity of motion generated from discrete locations and in echoic environments.