Some people use echolocation to get around. Here’s how it works

Many blind people navigate the world using a cane, guide dog or wearable GPS. But some have something more in their toolkit: echolocation. That’s the ability to sense nearby objects using sound. A new study shows just how master echolocators use this technique to get around.

These people make a sharp clicking sound with their tongue. (Watch the process in action.) Then they listen for its echo to sense where objects are around them. New brain-activity data show that with each click, expert echolocators improve these mental maps of their environment.  

Researchers shared these findings April 6 in eNeuro.

Clicking and listening for echoes can provide information about the location of nearby objects. Or their size. Maybe even their texture. (Bats use this same process to find their way as they flap through the night sky.)

Many studies have shown that in people, echolocation turns on parts of the brain that have to do with sight. They’ve also shown that echolocation improves a lot with practice.

But scientists still don’t know “how this happens,” says Santani Teng. “How the information builds in real time” beyond what can be learned from each individual echo. He and co-author Haydée García-Lázaro work at the Smith-Kettlewell Eye Research Institute. It’s in San Francisco, Calif. As cognitive neuroscientists, the two study how our brains think, learn and process information.

Mental mapping

To better understand human echolocation, they recorded clicks and echoes. They designed these echoes to act as if they were bouncing off a nearby object. Then, the scientists compared how two groups of volunteers responded to these recordings.

The four blind people in one group were all experts in echolocation. The other group of 21 people could see well. They also had no experience with echolocation.

Each volunteer listened to the recorded clicks followed by their echoes. The sounds were played in sets of two, five, eight or 11. After each set, these people were asked to decide whether an object had been to their right or left. As they listened, electrode caps on their heads recorded their brain activity.

The blind echolocators excelled at figuring out an object’s direction. They scored far better than those who could see. In fact, one echolocator figured out an object’s direction after hearing only two sets of clicks and echoes.

The brain data showed that each click-echo pair gives new details about the surroundings. Echolocators combine these additional details over time, “rather than through a single optimal snapshot,” says Monica Gori. She’s a neuroscientist who did not take part in this study. She works at the Italian Institute of Technology in Genoa. She also works with the Institute for Human & Machine Cognition in Pensacola, Fla.  

García-Lázaro says she and Teng want to learn more about “what exactly makes better echolocators.” She’s especially curious about how experts learn to ignore the click and focus only on its echo.

This “is not magic,” says Teng. “Echolocators have a truly remarkable skill, with real-life benefits.”