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Airdate: Nov 03, 2015
Scientist: Nicole Abaid

Bats - No Jams

Bats - No Jams
With a cave full of bats all flying and echolocating at the same time, how come they don't get in each other's way?

Transcript:
Bats - No Jams

Ambience: bats
We're listening to slowed down recordings of bat echolocations. With a cave full of bats all flying and echolocating at the same time, how come they don't get in each other's way? I'm Jim Metzner and this is the Pulse of the Planet.

Abaid: The thing with bat swarms is that when they do move in a group, they use echolocation to sense their environment, which means that their peers can hear it, and it has the potential to interrupt their sensing.

Nicole Abaid is an Assistant Professor in the Department of Biomedical Engineering and Mechanics at Virginia Tech.

Abaid: So, they make a sound with their voice usually ultrasound. It's higher-pitched than our ears can sense, but their ears can sense it. And then, they listen for the echo. So, the echo bounces off obstacles in the environment or some guy flying next to them, and when they hear the echo, they can tell the time difference between when they made the sound and when the echo comes back. And since they know sound takes a certain amount of time to travel a certain distance, they can tell how far away the thing is in front of them.

Abaid: So, the thing that makes the system complex is that all of the bats can hear the sounds. Within a species, you encounter scenarios where two bats may make a sound, and they generate a bunch of echoes. When they hear the echoes, there's confusion between whether or not the echo was generated by their sound or by another sound. That's called jamming, and that's a serious problem. But what's interesting in bats is that they don't seem to suffer from that.
We don't see massive collisions in bat swarms. And so, what the hypothesis we're working under is that bats have had this social reason to live together. So, they've also evolved ways to accommodate the problems that plague our engineering systems, who use a similar type of sensing. So, we want to understand what the bats do to be able to better control the engineering system.

More on swarming bats in future programs. I'm Jim Metzner and this is the Pulse of the Planet.