Ever heard of the "bat boy" aka Ben Underwood? What about Daniel Kisch? Both of these extraordinary individuals taught themselves to "see" using echolocation. Both were blind from a young age, but they taught themselves to explore their environment by well.. clicking their tongue.
By listening to the sound echoing back from the objects the sound wave hits, people like Ben Underwood and Daniel Kisch are able to determine how close or far away objects are. Ben and Daniel are able to negotiate tasks that are extremely difficult for many blind people; such as riding a bike.
While some small strides have been made to bring echolocation more widely to the blind community through either education on how to "click" with the tongue, much more work needs to be done. Scientists right now are experimenting with different devices that use ultrasound waves that are then amplified so the human ear can hear them.
And if blind people can see with echolocation, perhaps some will develop the expertise to be able to listen to sonar waves over long distances, like with submarines. Or perhaps in 50 years from now, the world's first blind radiologist will be able to put on his or her specially altered radiology glasses and earphone and diagnose patients merely by listening to amplified ultrasound waves.
Perhaps we're entering a brave new world, where blind people will be the most adept at remote sensing and interpreting medical ultrasounds because they've become accustomed to interpreting and understanding what substances these echoes represent.
Bring it on, science.
