The World’s Most Powerful Pair of Glasses—Part 3 of 3
If you have tuned in the last two weeks, you must be suitably impressed by Bailey the beluga. Not only can he and other whales “see” using sound, they can identify the size, shape, and texture of reflectors based on the nature of the reflections of sound from them. These animals pull off a second impressive physiological feat by controlling the gain of their auditory system to protect it from the loud echolocating clicks when they are produced but then rapidly increasing gain to receive the reflection.
So, are there other animals who can use sound to see? The answer to that question is definitely in the affirmative. Bats are famous for their use of echolocation to hunt in the darkness of the night. Even some cave-dwelling birds have rudimentary echolocating abilities. But what if I told you humans can see using sound as well. Do not believe me, just take a look at this video.
Daniel Kish is not the only human able to echolocate, but he certainly is one of the foremost experts. Not only does he ride a bicycle in regular traffic using echolocation, he even hikes on trails by himself using the reflections of the clicks he produces to guide him around obstacles and keep himself on the trail.
Kish and others who can use echolocation to replace the function of vision can be thought of as sophisticated users of sound who learn to discern sizes, shapes, distance, terrain, and texture through sound. Some of them have developed these skills and understand the acoustics well enough to teach others to use sound to navigate their environment. So, how exactly do they do this?
It is highly likely that most blind people use passive echolocation to gather information about their environment. Daniel Kish, and others like him however, actively produce clicks to sample their environment. These individuals have evolved astounding skills to see through sound and lead active and adventurous lives using their hearing to compensate for the vision they do not have.
Scientists have started exploring the neural substrates of successful echolocation in these experts. In experiments done using functional magnetic resonance imaging, scientists are discovering that the primary visual cortex is active during echolocation in blind experts. This suggests that neuroplastic changes allow redeployment of the visual areas of the brain to respond to acoustic stimuli – literally seeing through sound.
There, you have it—the world’s most powerful pair of glasses!