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Bats on Helium Reveal an Innate Sense of the Speed of Sound

by Scientific American
May 28th 2021
A new experiment shows that bats are born with a fixed reference for the speed of sound—and living in lighter air can throw it off.
you're ready to get back into yoga. So you ordered the essentials, a nonslip mat yoga blocks to keep balance and an exercise ball. And you use your Bank of America customized cash, rewards, credit card choosing to earn 3% cash back on online shopping and up to 5.25% as a preferred rewards member, which you put towards your most essential yoga gear. Noise, canceling headphones, apply for yours at Bank of America dot com slash More rewarding. Copyright 2021 Bank of America Corporation. Yeah, This is scientific Americans 62nd science. I'm Karen Hopkin. Mhm. Mhm bats rely on echolocation to navigate the night skies and to chase down and capture even erratically moving prey. But even more impressive than their aerial acrobatics are the mental gymnastics bats must be performing to translate the time it takes for their echoed calls to return into a distance to their target.

Now those pings would not normally be audible to our human ears, but we slowed them down so you can hear how a bat closes in on an object. Now, a new study shows that to get a leg up or a wing up on the necessary navigational calculations, bats have an innate sense of the speed of sound. The work appears in the Proceedings of the National Academy of Sciences. It has always been assumed that bats use the speed of sound in order to assess distance. So basically their brains measured time and then if they know the speed of sound, they can assess the distance to the target using it. You see level of tel Aviv University, but this assumes that they know the speed of sound. And this was never actually tested. That's where the helium comes in. one of the things we did is with two pops that were actually never exposed to regular air and we rear them an environment that is enriched in helium in order to see whether they will learn a new speed of sound because helium is lighter than air sound travels faster in a helium enriched medium, which means their echolocation sounds would come back faster, making objects seem closer than they really are.

Now, if bats learned to estimate distances based on the speed of sound they experience growing up pups raised in the presence of helium when they're later placed in a chamber of dense, regular air should act like targets are farther away, which means their echo location, pings should be longer and spaced farther apart than they were in the heli ox mix and longer and farther apart than the echolocation calls of pups that were raised in regular air and are therefore used to its density. But same logic the air pumps should mistake targets in hollyoaks as closer than they are and use echolocation pings that are shorter and more tightly spaced. We saw none of these Iran um Kay, now a postdoc at Dartmouth College, worked with these befuddled bats as a student in Yeovil's lab. They used the same values and they displayed the same sensory error no matter where they were born and raised. So that tells us it's basically in eight. In other words, in the heli ox makes all the pups acted as if their target was closer than it was, which means they all came to the table with an innate feel for the speed of sound based on a world filled with regular air.

And the same was true of adult bats, which also couldn't adjust their echolocation behavior to accommodate different concentrations of helium, they are unable to relearn a new reference to the speed of sound and that tells us that this is fixed and not flexible. This lack of flexibility might seem like a liability, especially because the speed at which sound travels can sometimes vary by a few percent depending on air temperature and humidity. But Yeovil hypothesizes that coming into the world with a fixed notion of the speed of sound is probably a plus. Many of these bats, you know, they're born in summer and they have two very quickly start flying and forging independently and therefore it's really important that they acquire their sensory, their echolocation sensing system ability is very, very rapidly and therefore it might be beneficial to have an innate reference and rather than something that you have to learn and might take time and you might learn an error some value, especially if you find yourself in a heli ox chamber in a certain lab in tel Aviv For Scientific, Americans, Science.

I'm Karen

Bats on Helium Reveal an Innate Sense of the Speed of Sound
Bats on Helium Reveal an Innate Sense of the Speed of Sound
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