Ask A Scientist
How does sonar work?
Asked by: Anthony Gianisis
School: Chenango Bridge Elementary School
Teacher: Mrs. Shafer
Hobbies/Interests: Sports, math, science
Career Interest: Scientist, electrical engineer
Answer from Mike Losinger
PhD Student in Biological Sciences
Research area: Animal behavior and communication, neurophysiology Interests/hobbies: Listening to music, reading, hiking, camping
The word "SONAR" stands for SOund Navigation And Ranging. For both humans and animals, it is a way to understand what’s around you using sound instead of sight. The main type of sonar that I’m going to talk about is called active sonar, also known as echolocation. Many animals use echolocation to understand the world around them, including bats, dolphins, whales, and even two species of birds. Humans also use echolocation with special machines, in boats and submarines. Echolocation is very useful when simple sight isn’t enough. If you’ve ever heard an echo of your own voice, you’ve already taken the first step toward using sonar!
The way that it works is that a source (animal, submarine, etc.) sends out a sound into whatever environment that it’s in, usually underwater or through the air. This sound is usually very high-pitched or very low-pitched, and it doesn’t last very long. For submarine sonar, these sounds are called "pings", and for animals these sounds are called "clicks" or "pulses." After being sent out, the sound bounces off all the objects in the environment and then returns to the listener with an echo. In animals, this echo is picked up by very sensitive ears, and in submarines, by special listening devices. For example, bats have very large ears just for this purpose.
Every time that a sound bounces off of an object, its loudness and pitch (how high or low it is) change. These sounds change based on the size of an object and how far the listener is to that object. So when the echo comes back to the listener, it now shows a kind of "map" of all the objects that it bounced off of in the environment. Most humans can’t tell what objects are around them just from the echoes they hear. This is because our brains haven’t evolved to use echolocation to make these "maps." However, some blind people have learned to use it! Similarly to bats and dolphins, some blind people use clicking sounds with their mouth or with a special device in order to "see with sound."