Cross-modal interactions for the passive experimental context (Exp. 1). Scatter plot of the subjective audio and video scores with their 95% confidence intervals obtained for different combinations of audio and video levels. Vertical and horizontal lines connect data points obtained for similar audio and video quality levels, respectively (La1, La3, and La7 for audio and Lv1, Lv3, and Lv7 for video). The dashed blue lines represent isoquality lines in the absence of cross-modal interactions.