Perceptual thresholds of audio-visual spatial coherence for a variety of audio-visual objects

Audio-visual spatial perception relies on the integration of both auditory and visual spatial information. Depending on auditory and visual features of the stimulus, and the relevance of each sound to the listener, offsets between both signals are more or less acceptable. The current paper investigates to which extent each of these factors influences how critical the perception of spatial coherence is by estimating the psychometric function for seventeen audio-visual stimuli. The results show that the maximum accepted offset angle does not depend on semantic categories but is linked to audio feature classes with harmonic sounds leading to greater acceptable offsets. A regression shows that the perceptual spectral centroid is negatively correlated with the offset angle and the slope of the psychometric spatial-coherence function. This finding, however, is not conclusive and further research is necessary to define all parameters that influence bimodal localization of realistic stimuli.