What Is Echolocation? Definition and Examples in the Animal and Human Worlds

Some species of bats use echolocation to hunt at night
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Echolocation is a physiological process that certain animals use to locate objects in areas of low visibility. The animals emits high-pitched sound waves that bounce off objects, returning an “echo” and providing them information about the object’s size and distance. This way, they are able to map out and navigate their surroundings even when unable to see.

The skill is mainly reserved for animals who are nocturnal, deep burrowing, or live in large oceans. Because they live or hunt in areas of minimal light or complete darkness, they have evolved to rely less on sight, using sound to create a mental image of their surroundings instead. The animals' brains, which have evolved to understand these echoes, pick up on specific sound features like pitch, volume, and direction to navigate their surroundings or find prey.

Following a similar concept, some people who are blind have been able to train themselves to use echolocation by clicking their tongues.

How Does Echolocation Work?

To use echolocation, an animal must first create some kind of sound pulse. Typically, the sounds consist of high-pitched or ultrasonic squeaks or clicks. Then, they listen back for the echoes from the emitted sound waves bouncing off objects within their environment.

Bats and other animals that use echolocation are specially tuned to the properties of these echos. If the sound comes back quickly, the animal knows the object is closer; if the sound is more intense, it knows the object is bigger. Even the echo’s pitch helps the animal map its surroundings. An object in motion towards them creates a higher pitch, and objects moving in the opposite direction result in a lower-pitched returning echo.

Studies on echolocation signals have found genetic similarities between species that use echolocation. Specifically, orcas and bats, who’ve shared specific changes in a set of 18 genes connected to cochlear ganglion development (the group of neuron cells responsible for transmitting information from the ear to the brain).

Echolocation isn’t just reserved for nature anymore, either. Modern technologies have borrowed the concept for systems like sonar used for submarines to navigate, and ultrasound used in medicine to display images of the body.

Animal Echolocation

The same way that humans can see through the reflection of light, echolocating animals can “see” through the reflection of sound. The throat of a bat has particular muscles that allow it to emit ultrasonic sounds, while its ears have unique folds that make them extremely sensitive to the direction of sounds. While hunting at night, bats let out a series of clicks and squeaks that are sometimes so high-pitched that they are undetectable to the human ear. When the sound reaches an object, it bounces back, creating an echo and informing the bat of its surroundings. This helps the bat, for example, catch an insect in mid-flight.

Studies on bat social communication show that bats use echolocation to respond to certain social situations and distinguish between sexes or individuals, as well. Wild male bats sometimes discriminate approaching bats based solely on their echolocation calls, producing aggressive vocalizations towards other males and courtship vocalizations after hearing female echolocation calls.

Toothed whales, like dolphins and sperm whales, use echolocation to navigate the dark, murky waters deep beneath the ocean’s surface. Echolocating dolphins and whales push ultrasonic clicks through their nasal passages, sending the sounds into the marine environment to locate and distinguish objects from near or far distances.

The sperm whale’s head, one of the largest anatomical structures found in the animal kingdom, is filled with spermaceti (a waxy material) that helps sound waves bounce off the massive plate in its skull. The force focuses the sound waves into a narrow beam to allow for more accurate echolocation even over ranges of up to 60 kilometers. Beluga whales use the squishy round part of their foreheads (called a “melon”) to echolocate, focusing signals similarly to sperm whales.

Human Echolocation

Echolocation is most commonly associated with non human animals like bats and dolphins, but some people have also mastered the skill. Even though they aren’t capable of hearing the high-pitched ultrasound that bats use for echolocation, some people who are blind have taught themselves to use noises and listen to the returning echoes to make better sense of their surroundings. Experiments in human echolocation have found that those who train in “human sonar” may present better performance and target detection if they make emissions with higher spectral frequencies. Others have discovered that human echolocation actually activates the visual brain.

Perhaps the most famous human echolocator is Daniel Kish, president of World Access for the Blind and an expert in human echolocation. Kish, who has been blind since he was 13 months old, uses mouth clicking sounds to navigate, listening to echoes as they reflect from surfaces and objects around him. He travels the world teaching other people to use sonar and has been instrumental in raising awareness for human echolocation and inspiring attention among the scientific community. In an interview with Smithsonian Magazine, Kish described his unique experience with echolocation:

It’s flashes. You do get a continuous sort of vision, the way you might if you used flashes to light up a darkened scene. It comes into clarity and focus with every flash, a kind of three-dimensional fuzzy geometry. It is in 3D, it has a 3D perspective, and it is a sense of space and spatial relationships. You have a depth of structure, and you have position and dimension. You also have a pretty strong sense of density and texture, that are sort of like the color, if you will, of flash sonar.