If you’re a human being, that’s probably something of a surprise, since the chances are that you can’t hear them at all. We all know they use sound for echolocation, but those sounds are simply too high-frequency for most humans to hear. You might be very lucky, particularly if you’re young, and just be able to pick out their squeaks right at the edge of your perception, but even then it’s so marginal that you’re only catching a tiny part of the sound intensity bats emit. It turns out that bats are some of the loudest animals on the planet, with some species able to emit sounds up to 130db, which is just about the threshold at which sounds become painful to humans and significantly louder than the inside of a nightclub or watching a jet take off from 100M.
I find it amazing that something can be so incredibly loud, and yet seem completely silent to me. It’s weird to think of those quiet summer evening I’ve spent watching them flit about overhead being set against a deafening crescendo of noise. Nature never ceases to amaze.
All of this, incidentally, came out of a piece by Ed Yong, at Not Exactly Rocket Science, about a species of bat that has evolved much quieter squeaks in order to sneak up on the moths it preys on. It’s fascinating; go read.
And if you’re interested in little-known bat trivia, did you know that they account for a quarter of all mammal species?