when a bat wants to fly, it uses the echolocation sensing technique to navigate. The bat sends out an high-frequency sound pulse, usually from its mouth or nose. when the sound pulse bounces off an object, the echo comes back to the bat. the work of two scientists in the late 1700s led to a greater knowledge of bats. they found that bats could not navigate properly if their hearing was blocked or the bats had small bags over their heads. donald griffen proved that bats uesd the echoes from the ultrasonic signals to navigate.