The bat reads the sound and can tell where its prey is and then eat it. Bats are not deaf. People only invent myths about bats to scare other people. Bats don't have rabies and they can't turn into vampires. They don't mean any harm, but when they are flying around in a room th ey only want to find an exit.
Bats are good.
Without bats the world would be filled with deadly bugs and big mosquitoes that can kill you. In the winter when it gets cold, bats either hibernate or migrate. While one sex is migrating, the other is hibernating. When bats migrate some bats may fly over 800 miles to get to their hibernacula. This helps them get to their winter roosts much quicker.