Speaker
Description
When a vehicle approaches, there are several acoustic cues that can inform about the arrival time of the vehicle (time-to-collision, TTC), such as the change in intensity at the pedestrian’s position or the change in azimuthal angle. But which cues do we actually make use of? To answer this question, we manipulated the availability of sound level and angle cues. In the normal condition, both the sound intensity and the azimuthal angle of the simulated sound sources changed dynamically as the vehicle approached. In a level-[DO1.1]fixed condition, the intensity at the participants position did not change dynamically but instead corresponded to a static vehicle position, while the angle of the simulated sound sources changed during the approach. In an angle-fixed condition, the simulated sound sources remained at a static position, while the sound level changed during the approach. Within each condition, we varied the presented TTC as well as the size, speed, and sound power of the vehicle, and the presence of a reflecting ground surface. When angle cues were removed, participants showed an increased overestimation of the TTC, but the estimated TTC clearly followed the presented TTC. In contrast, when the level cues were removed, participants’ estimates varied only little with the presented TTC, showing a strong central tendency effect. At short TTCs, where the largest changes in angle occur, the estimated TTCs still reflected some consideration of the presented TTC. This demonstrates that in the absence of level cues, participants could make some use of angle cues, but level cues most strongly contribute to the arrival time estimation.