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How do whales use sound to communicate across long distances?

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Illustration showing various cetaceans, including baleen whales like the blue whale, fin whale, humpback whale, gray whale, sei whale, northern right whale, and bowhead whale, as well as toothed whales such as the sperm whale, narwhal, beluga, Baird's beaked whale, killer whale, dolphins, and porpoises. Each species is labeled with its scientific name and typical or maximum length, with a size scale in the corner for reference. — cetacean Whales (order Cetacea).

Whales communicate across long distances primarily by producing low-frequency sounds, which are highly effective for long-range transmission in the ocean. Because water is an excellent conductor of sound, these powerful, low-frequency vocalizations—such as those produced by baleen whales—can travel across entire ocean basins.123

To generate these signals, baleen whales use a U-shaped ridge of tissue at the top of their larynx, recycling air to sing underwater. These songs, which may serve to identify pod members or assist in navigation, can carry for thousands of kilometers. The efficiency of this communication is further enhanced by the physical properties of the ocean; for instance, sound generated within the SOFAR channel—a deep-ocean zone of minimum sound speed—can become trapped by refraction and travel vast distances.123

However, this vital biological process is increasingly threatened by noise pollution from human activities like shipping, which occupies the same frequency bands used by whales, thereby hindering their ability to communicate effectively.23