Echolocation are sound waves used by many living beings to locate objects, communicate and navigate. Most sea mammals (such as the whale) use echolocation as a way to see. Like in murky waters.
Bats are one of the many beings that use echolocation. They send the sound waves mostly through their mouths although some use their noses. Using echolocation, bats can use it to find food and know what’s around them. How this works is, the sound reflects off the objects and is picked up by the bat’s sensitive ears. The frequencies sent out are so high that humans are unable to pick up the sound waves.
Like I said, most marine mammals use echolocation to see. They use it by detecting echoes of sounds and use them to produce 3-Dimensional information. Take dolphins for example, they make sounds by squeezing air through their nasal passages that’s under the blowhole. There is a fat filled area on the dolphin’s forehead that is like a lens which focuses on the sound waves ahead of the dolphin. The sound waves that are given then bounces off the objects and is received through the dolphin's lower jaw.
With bats and marine life, humans also use echolocation. Blind people have learned to use echolocation as well so they can interact with the environment and have used it to see. Humans use it by creating sounds. They may tap their canes, gently stomp their foot, snap their fingers or even make clicking noises. People who have learnt how to use echolocation can make out the sound waves that have been reflected off from nearby objects. This gives them a good idea of where they are.