How Does a Dolphin's Sonar Work?

Dolphins are marine mammals that live throughout the world. They live in groups called pods, and communicate with each other by whistling and squeaking. They also have the ability to use sonar, which is called echolocation, to communicate and to hunt their food.

  1. Sending

    • To use their sonar, dolphins send out powerful sound waves. They do this by making a clicking sound, which goes out into the surrounding water as a narrow beam of sound. When air passes over water at a dolphin's blowhole, parts of the dolphin's forehead vibrates in response. The vibration is the clicking sound, which projects waves of sound.

    Receiving

    • After the sound waves leave the dolphin, they travel through the water until they hit something, and then bounce back. The dolphin senses the returning sound waves in its lower jaw, which is filled with acoustic fat. This fat allows the dolphin to feel the vibration of the returning sound wave.

    "Seeing"

    • Dolphins judge how far away an object is and how quickly it is moving based on how long the sound wave took to bounce back to them. They also use the fat in their jaw to determine in which direction the object is located. Echolocation is so complex that a dolphin can even tell how large the object is, how it is shaped and how solid it is based on how strongly the sound waves bounce back.

    Interference

    • Because dolphins use sonar to hunt and communicate, they run into difficulties when their sound waves bounce off other sound waves. Humans often produce sound waves underwater, deliberately or accidentally, which is called anthropogenic noise. This can include sonar testing, offshore drilling and loud noises meant to herd fish. These huge sound waves can disorient dolphins or hurt them. Dolphins that have too much exposure to human-made noise can lose their hearing, beach themselves or suffer in other ways.