Human Echolocators Have Better Localization Off Axis

Here, we report novel empirical results from a psychophysical experiment in which we tested the echolocation abilities of nine blind adult human experts in click-based echolocation. We found that they had better acuity in localizing a target and used lower intensity emissions (i.e., mouth clicks) when a target was placed 45 degrees off to the side compared with when it was placed at 0 degrees (straight ahead). We provide a possible explanation of the behavioral result in terms of binaural-intensity signals, which appear to change more rapidly around 45 degrees. The finding that echolocators have better echo-localization off axis is surprising, because for human source localization (i.e., regular spatial hearing), it is well known that performance is best when targets are straight ahead (0 degrees) and decreases as targets move farther to the side. This may suggest that human echolocation and source hearing rely on different acoustic cues and that human spatial hearing has more facets than previously thought.

Automated summary

This study reports novel empirical results from a psychophysical experiment testing the echolocation abilities of nine blind adult experts. The findings show that these experts had better accuracy in localizing a target when it was placed at 45 degrees off to the side, and they used lower intensity emissions in such cases. An explanation is provided based on binaural-intensity signals, which change more rapidly around 45 degrees. The surprising result suggests that human echolocation and source hearing rely on different acoustic cues, indicating a more complex nature of human spatial hearing.