Bats and Echolocation
Echolocation can sound at more than 120 decibels, which is right around the pain threshold of the human ear. Thankfully, it's at a frequency that we can't hear. Bats disable their hearing when they send out the call that triangulates their prey, then turn it back on to receive the resulting echoes. They do this by contracting the muscles in their ears hundreds of times per second.