Bats find their next meal primarily by sending out high-pitched sound waves and using their ears to determine approximately where the nearest objects are. This process of finding prey by judging echoes is called echolocation.
Although bats are not blind, they do not rely on their eyes to hunt, especially since they are nocturnal creatures that do their feeding in the dark. Their eyesight is very poor, but bats make up for this with their large ears, which they use to collect reflected sounds to track their targets. Bats then use the information gathered from the echos to determine how near an object is, how big it is and which direction it's moving.