Whether out fighting crime on the streets of Gotham or just trying to find those misplaced car keys, the use of bat-like sonar techniques could really make life easier for us. Fortunately, new research suggests that we humans may in fact possess echolocation capabilities that can be honed, as demonstrated by a group of participants who were able to identify objects simply by bouncing sounds off them.
Echolocation is a technique used by animals such as bats and dolphins to determine the shape and location of unseen objects by emitting a high-frequency sound and listening for the echo. While it helps certain species to hunt prey, previous research has indicated that some visually impaired people may also be able to develop the technique in order to judge spaces and improve their navigation skills.
To test whether unpracticed individuals can also use echolocation, researchers recruited 15 sighted people to take part in an experiment in which they had to distinguish between two 3D-printed cylinders with differing geometries. With the objects obscured from view, participants were instructed to use a mobile device to emit a high-frequency buzzing sound, before analyzing the nature of the echo in order to determine which of the two cylinders was being targeted.
The device emitted tones of up to 41 Hz, which is in the range used by bats for echolocation but is too high for humans to hear. A sensor was therefore set up to receive the echoes bouncing back off the target objects, which were then downscaled to one-eighth of the original pitch and delivered to participants through headphones.
Reporting their findings in the journal PLOS ONE, the study authors reveal that participants were successfully able to identify which of the two cylinders was being targeted as long as the objects were rotating rather than stationary. Because one of the cylinders featured twice as many convex surfaces as the other, listeners were able to observe changes in the intensity, pitch, and timbre – or sound quality – of the echo as the objects rotated.
However, participants were less successful at distinguishing between the two cylinders if they were kept stationary, as a lack of time-dependent changes in the nature of the echo made it more difficult to identify the geometric characteristics of each object.
Summing up their findings, the study authors conclude that “time-varying echo information is effective for identifying target geometry through human echolocation,” implying that – like bats and dolphins – we may indeed have the capacity to interact with the world around us using sonar.