The blue whale is known for producing the largest known animal sound.
Blue whale calls are low-frequency, powerful vocalizations that can reach about 188 decibels relative to one micropascal at one metre, although exact values vary with measurement method. Their sounds travel efficiently through seawater and may carry across very long distances.
These calls are associated with communication, particularly among widely separated animals. Blue whales often feed in productive areas where krill gather, but their populations may be spread across enormous ocean regions. Low-frequency sound is useful in that environment because it travels farther than high-frequency sound.
The decibel figure must be interpreted carefully: underwater decibels use a different reference pressure from air measurements, so an underwater value cannot be compared directly with a concert or aircraft figure. Sperm whales produce extremely loud echolocation clicks, while humpback whales are famous for complex songs, but the blue whale is the standard record-holder for source level.