Brain structures that process visual information in sighted people process echo information in blind echolocation experts. ~ Canadian psychologist Lore Thaler et al
As an infant, American Daniel Kish had retinoblastoma: an aggressive cancer that attacks the retinas. To save his life, both eyes had been removed by the age of 13 months.
Nowadays, as a social grace, he wears prosthetic eyeballs, which get gummy and need cleaning a couple times a day.
At 2 years old, Kish naturally developed a click acoustically ideal for echolocation. The click sound waves travel at more than 300 meters per second, bounce off objects, and make their way back to the ear at the same rate.
That’s good, but hardly compares to bats, which click and hear at much higher frequencies, enabling bats to navigate their way through a crowd of thousands of other bats and nab millimeter-sized insects on the fly.
Bats can get detailed pictures of their immediate environment at incredible speed despite having a brain many times smaller than the human auditory cortex. It is an exemplary proof that the brain is only a facsimile. Mental processing is entirely an energetic exercise, with diffident physical correspondence.
Kish can tell a building 300 meters away, a tree from 9 meters, and another person from 2. He can tell the difference between a car, a pickup truck, and an SUV. Up close he can echolocate a 3-cm pipe.
Echolocation works thanks to stereo 3d ears: an ear on each side of the head and depth perception by mental processing. A noise off to one side reaches the closer ear a millisecond (1/1,000th second) sooner: enough gap for the human auditory complex to process. People can process sound a very few degrees off-center.
Like recognizing a voice in a crowd, Kish can hear his sonic reflections amid tremendous ambient noise. A detailed picture emerges, though of course without color. Flowers sound soft, while stones echo hard and crisp.
Echolocation is not easy for humans to master. Kish, who teaches echolocation, compares it learning to play the piano: anyone can get the basics, but very few play Carnegie Hall. Only 10% quickly catch on.
The National Federation of the Blind, jealous of Kish, is the blind leading the blind. Its executive director strains to politely observe about Kish, “let’s just say he is unique.” Their way is learning how to use a long white cane.