Sounds are perceived as louder when accompanied by visual movement

In this study, we present three experiments investigating the influence of visual movement on auditory judgements. In Experiments 1 and 2, two bursts of noise were presented and participants were required to judge which was louder using a forced-choice task. One of the two bursts was accompanied by a moving disc. The other burst either was accompanied by no visual stimulus (Experiment 1) or by a static disc (Experiment 2). When the two sounds were of identical intensity participants judged the sound accompanied by the moving disc as louder. The effect was greater when auditory stimuli were of the same intensity but it was still present for mid-to-high intensities. In a third, control, experiment participants judged the pitch (and not the loudness) of a pair of tones. Here the pattern was different: there was no effect of visual motion for sounds of the same pitch, with a reversed effect for mid-to-high pitch differences (the effect of motion lowered the pitch). This showed no shift of response towards the interval accompanied by the moving disc. In contrast, the effect on pitch was reversed in comparison to what observed for loudness, with mid-to-high frequency sound accompanied by motion rated as lower in pitch respect to the static intervals.The natural tendency for moving objects to elicit sounds may lead to an automatic perceptual influence of vision over sound particularly when the latter is ambiguous. This is the first account of this novel audio-visual interaction.