Subjective evaluation of the audiovisual spatial congruence in the case of stereoscopic-3D video and Wave Field Synthesis

While 3D cinema is becoming increasingly established, little effort has focused on the general problem of producing a 3D sound scene spatially coherent with the visual content of a stereoscopic-3D (s-3D) movie. The perceptual relevance of such spatial audiovisual coherence is of significant interest. In this paper, a subjective experiment is carried out where an angular error between an s-3D video and a spatially accurate sound reproduced through Wave Field Synthesis (WFS) is simulated. The psychometric curve is measured with the method of constant stimuli, and the threshold for bimodal integration is estimated. The impact of the presence of background noise is also investigated. A comparison is made between the case without any background noise and the case with an SNR of 4 dBA. Estimates of the thresholds and the slopes, as well as their confidence intervals, are obtained for each level of background noise. When background noise was present, the point of subjective equality (PSE) was higher (19.4◦ instead of 18.3◦) and the slope was steeper (−0.077 instead of −0.062 per degree). Because of the overlap between the confidence intervals, however, it was not possible to statistically differentiate between the two levels of noise. The implications for the sound reproduction in a cinema theater are discussed.