Investigations Into the Velocity and Distance Perception of Moving Sound Sources

Temporal loudness changes, binaural cues and Doppler shift can all influence distance perception of moving sound sources. This article will analyze different auditory distance perception cues of moving sound sources. In psychoacoustic experiments, the subjects were presented with dichotic and diotic stimuli of a set of reallife recordings taken from a passing passenger car and then asked to determine the velocity of the object and its minimal distance from the listener. The results of the listening experiments allow us to separate monaural distance perception cues from binaural ones, and thus show that binaural cues contribute significantly to the perception of velocity. For short distances and high velocities, the presentation of binaural cues causes a decrease in the perceived velocity while for long distances and low velocities this causes a clear increase. By estimating the minimal distance from the passing object, one observes a significant difference between dichotic and diotic presentation, which can be explained by an increased loudness of dichotic stimuli due to the binaural masking level difference (BMLD). Furthermore, it is shown that the main parameter for distance determination is the maximum sound pressure level at the listener's position. However, dynamic cues (change of sound pressure level over time, Doppler shift) are of considerable importance for the plausibility of the auditory scene.