It’s now well-established that bats can develop a mental picture of their environment using echolocation. But we’re still figuring out what that means—how bats take the echoes of their own vocalizations and use them to figure out the locations of objects.

In a paper released today, researchers provide evidence that bats engage in echolocation in part because they’re born with an innate sense of the speed of sound. How did the researchers study this phenomenon? By raising bats in a helium-rich atmosphere, where the lower-density air produces an increase in the speed of sound.

Putting the location in echo

Echolocation is rather simple in principle. A bat produces sound, which bounces off objects in their environment and then returns to the bat’s ears. For more distant objects, the sound takes longer to return to the bat, providing a sense of relative distance.