Difference in auditory time-to-contact estimation between the rear and other directions

Time-to-contact estimation is essential for individuals to avoid collision with externally moving objects. Although the auditory system plays an important role in detecting events from all directions around listeners including events out of sight, it is still unclear how the auditory system contributes to the time-to-contact judgment. The present study investigated whether the auditory time -to-contact changed depending on the direction of the approaching sound (0 degrees, 45 degrees, 90 degrees, 135 degrees, or 180 degrees). The results demonstrated that auditory time-to-contact judgments were underestimated compared to actual auditory time-to-contact for all directions, thus replicating the classical time-to-contact underestimation effect. In contrast, the trends observed for the auditory time-to-contact judgment for a sound stimulus approaching from behind differed from those approaching from the front, even though the auditory distance localization performance did not differ for the different angles. This difference in estimation between the sound approaching from the rear and other directions could be attributed to the sound coming from behind being more emotionally negative than the sound coming from the front.