Human echolocation

How it works

Sound bounces off objects. A sharp click of the tongue against the roof of the mouth makes a short, wide-band sound that returns as an echo a few milliseconds later¹. The delay tells you distance. The difference between the two ears tells you direction. The tone of the echo tells you something about size and texture. A wall sounds different from a tree, and a tree sounds different from a parked car¹.

Every brain does some of this already. Blind people who use it on purpose become very precise. Expert clickers can detect an object the size of a dinner plate from a few metres away and tell a flat surface from a curved one¹.

In 2011, researchers in Canada scanned two blind echolocation experts. When they listened to recordings of their own clicks and echoes, their primary visual cortex became active. Sighted control subjects showed no such activity¹. The brain region built for sight was processing sound. The skill can be learned. In a 2021 study, blind and sighted volunteers trained for ten weeks. They improved on echo tasks and showed increased visual cortex activity¹.

Try it

1. Sit in a quiet room with your eyes closed.
2. Hold a large plate or a hardback book about 30 cm in front of your face.
3. Make a steady “shhh” sound, or repeated tongue clicks.
4. Slowly move the plate towards and away from your face. Listen for the sound becoming brighter and fuller as the plate gets closer.
5. Have someone else move the plate while you say when it is close. Most people can do this within a few tries.

History and culture

Daniel Kish, an American born in 1966, lost both eyes to retinoblastoma, an eye cancer, before he was 13 months old². He taught himself to click as a toddler. He rides a bicycle, hikes alone, and has taught his method, which he calls flash sonar, to more than 500 blind children through his organisation World Access for the Blind². His TED talk in 2015 brought the skill to a wide audience².