Blind and sighted people alike can learn to 'see' with echolocation, study finds

Many technologies exist to assist people who are blind or have limited vision to manage daily life. But even without technology, people — regardless of whether they could see or not — can learn the ability to echolocate like bats and whales to see the world around them using sound.

Scientists in the U.K. conducted an experiment in which a group of sighted and blind people were given a 10-week course on how to echolocate. Their results, published earlier this year in the journal Cerebral Cortex, suggest that our brains have an extraordinary capacity to adapt, regardless of visual ability. 

In the early 1980s, when I was a roving reporter for CBC Radio's Morningside with Peter Gzowski, I visited the Canadian National Institute for the Blind in Toronto. There, I interviewed Geoff Eden who was responsible for new emerging technologies to assist people who are blind.

Eden, who is blind himself, introduced me to a variety of devices including a beeping soccer ball, early voice synthesizers for computer screens and braille keyboards and printers. Then he said, "There is another device I would like to show you but it is in another building. Follow me."

He proceeded out the door and down the hallway at a brisk pace — and he did not use a white cane, used by many people who are blind to scan their surroundings for obstacles. (The colour white helps onlookers identify them as blind.)

I followed him to the end of the hall, around a corner, out a door to a parking lot, between several cars without slowing down, then through another door in an adjacent building. 

His navigation abilities astounded me. I could understand how he would know the layout of the buildings, but a parking lot that changes from day to day? So I asked, "Geoff, are you fully blind, or do you have partial vision?" 

"Nope. Blind as a bat," was his reply.

I asked, "So how did you navigate between the cars in the parking lot?"

"Did you notice how I rattle my keys in my pocket as I walk? That's my sonar."

Edenwent on to explain how he used echoes from the high-pitched sound of his jingling keys to identify nearby objects and how far away they are.

He then demonstrated how he could tell exactly where a wall was. 

With his hands at his sides, he walked straight toward a wall and stopped with his nose a few centimetres from the surface. He also showed how his voice sounded different when close to the wall compared to farther away.

Sound was his way of seeing the world. 

On a 2017 episode of Quirks & Quarks we met Brian Borowski, who uses clicks made with his tongue against the roof of his mouth to identify objects as small as 20 centimetres in length. Both he and Eden could identify walls, doors, windows, and outside, cars, fences and even lampposts just using sound.

We often hear how people who've lost one sense, like those who are blind or deaf, gain an enhanced ability to sense their surroundings through a different sense, especially if they lost their sense early in their lives. Blind people may hear better and deaf people may see better.

This week on Quirks & Quarks, I spoke with Lore Thaler, senior author of the Cerebral Cortex study, who investigated if sighted individuals could also boost their ability to use sound to visually sense their surroundings through practice. 

Quirks and Quarks7:48Sighted and blind people can learn to echolocate equally well

She analyzed the brains of people, with and without sight, before and after their 10 weeks of echolocation training during which all participants with any ability to sense light were blindfolded. She was interested in how their brains change when they use sound for visual references.

The training program consisted of 20 sessions, each lasting two to three hours, where the participants practiced different tasks like navigating a maze or determining the size of something, as well as getting around real environments under the guidance of one of the experimenters using only click-based echolocation. 

Thaler found that after they trained to "see" with sound through echolocation, all the participants showed changes in their audio and visual portions of their brains. It didn't matter if the person could see or not.

This means that our brain's primary visual cortex at the back of the brain that normally only processes visual sensory information coming through our eyes, can also respond to sound. It's a clear demonstration of our brain's ability to continually learn and form new pathways.

In a recent email, Eden told me: "For many of us who rely on echolocation, and especially those who had sight, [we] build an inner picture in our minds of our environment. Hence, there is no question in my mind of the visual circuits of the brain being reassigned to hearing."

"For echolocators, the challenge with aging is the reduction in high-frequency hearing. Sharp high-frequency clicks give the best resolution, hence a reduction in accuracy with age. I don't 'see,' like I used to."

Perhaps there is a lesson here for all of us to pay more attention to the sounds around us. There is much more information reaching our ears than chirping birds, wind in the trees, traffic, voices and music.

Using sound to be more aware of the environment enhances our experience and could come in handy as we age and vision begins to deteriorate.