What mammal produces the loudest sound of any animal?

The mammal that produces the loudest sound of any animal is the sperm whale. Its powerful echolocation clicks can reach a reported source level of about 236 decibels underwater.

Sperm whales use these clicks to navigate and hunt in the deep ocean, where sunlight disappears and visibility is extremely poor. Sound is produced by forcing air through specialized structures called phonic lips near the front of the head. The whale's large spermaceti organ and related tissues help focus the sound into a directional beam.

The clicks are far louder than most familiar animal calls, but decibel comparisons underwater and in air are not directly interchangeable. That is why claims about the “loudest animal” can cause confusion. Blue whales produce extremely powerful low-frequency calls and are often described as the loudest whales by vocal volume or long-distance communication, while sperm whales hold the standard record for the loudest measured animal sound.

Sperm whales also have the largest brain of any animal and can dive to extraordinary depths. Their clicks serve both echolocation and communication, including patterned sequences known as codas.