Approaching background sounds extend the duration of foreground auditory stimuli.

Time estimation is crucial to deal with external objects, either for their timely avoidance or interaction. Studies on the effect of approaching sounds on time estimation reported that these stimuli produce time overestimations, generally interpreted as an acceleration of the internal clock due to the attention/arousal prompted by potential approaching objects. Yet, in these studies the moving sounds were also the targets of time estimations, potentially generating confounds. Here we investigated the effect of background moving sounds on the perceived duration of separate foreground stimuli. Moreover, we provided an explicit computational model illustrating how changes in background moving sounds affect time estimation. Three groups of blindfolded participants passively listened to (background) approaching, receding, or scrambled (control) motion sounds, which were rendered using sensory substitution. Meanwhile, participants were presented with sinewave tones of different durations, which were estimated by participants using the reproduction method. The group exposed to the approaching background sound significantly overestimated the duration of the tones. This suggests that even background moving sounds can elicit the attentional/perceptual mechanism responsible for accelerating the internal clock. Moreover, shorter tones tended to be overestimated, and longer ones underestimated (Vierordt effect), indicating Bayesian regression toward the mean duration, which was successfully captured by our model.