Figure 6. Results of Experiment 2, in which distance and duration noise were added to the standards to force discrimination based on speed.

Each column corresponds to a different listener (L1-L4); each row is a different standard “mean”, corresponding to the standard values given along the major negative diagonal of Figures 3 and 4. The results show that the auditory system is sensitive to speed: when distance and duration cues are made uninformative, listeners are able to discriminate stimuli based on speed alone.