Sperm Whales Seem to Change Their Calls When Ships Are Near, Highlighting the Implications of Underwater Noise Pollution

Several of the huge cetaceans living in the eastern Caribbean Sea shortened the intervals between their clicks and used one click pattern more than another when vessels were around, according to a new study

August 6, 2026 11:12 a.m.

A growing body of research on sperm whales, Earth’s largest toothed whales, suggests that human language might not be as unique as we thought. In fact, scientists at the nonprofit Project CETI (Cetacean Translation Initiative) are working to translate sperm whale communication—which seems to encompass different dialects, for starters.

In 2024, they revealed that the highly social species uses a so-called “phonetic alphabet” made up of codas, or distinct series of clicks, that seems to be the foundation of their language. Now, the initiative has yielded another surprising finding.

Sperm whales appear to change their chatter in the presence of underwater noise from shipping vessels, researchers reported in a study published on June 18 in the journal Ecological Informatics. When boats were around, the massive creatures shortened the intervals between clicks and used one type of coda more than another, leading to an extremely important question.

“Are whales talking about the ships, or is it an impact on their voices because the ships are around?” says study co-author David Gruber, founder and president of Project CETI, to the Guardian’s Emma Bryce.

Gruber and his colleagues examined more than 1,0000 codas produced by 13 sperm whales living off the Caribbean island of Domenica. They were recorded between 2014 and 2016 via acoustic tags attached to each animal. Nearby vessels were detected via background noise in audio recordings and a database of shipping reports.

The team compared the sperm whales’ use of two different vowel-like click patterns, known as a-codas and i-codas, in the presence and absence of ship sounds. The acoustic properties of a-codas resemble the “a” vowel in human speech, while i-codas resemble those of the “i” vowel.

diagram showing difference between presence of ship noise and absence — Sperm whales communicate in different series of clicks called codas. Researchers have recently identified two that resemble vowels, called the a-coda and i-coda. R. Diamant et al., *Ecological Informatics*, 2026 under CC BY 4.0

Analyses revealed that the whale “vowels” changed both structurally and temporally amid noise pollution from boats. The sperm whales emitted many more a-codas than i-codas, and the codas were faster, meaning the time between clicks was shorter.

“The spacing between each click becomes really compressed,” Gruber tells Popular Science’s Laura Baisas. “We call it the interclick interval.” The team could even predict whether ships were near based on the whales’ click patterns.

The study particularly stands out because it “shows changes to the fine-scale content of those calls,” says Nathan Merchant, an underwater bioacoustics expert at the U.K. government’s Centre for Environment Fishers and Aquaculture, to the Guardian. “It really adds another dimension of nuance to that story about how underwater noise can affect cetaceans,” says Merchant, who wasn’t involved in the study.

Did you know? Whale language evolution

All sperm whales in the Mediterranean Sea were thought to be part of one cultural group, identifiable by a unique coda. But those in the east—the opposite end of where the animals are thought to have entered the sea round 20,000 years ago—might have developed a distinct dialect from those in the west, according to a study published in June.

In the presence of underwater shipping sounds, the researchers also struggled to identify each coda type, making classification difficult. This suggests that the whales might be having a hard time hearing and understanding one another’s calls, too, reports National Geographic’s Richard Kemeny.

The findings are especially relevant now, as underwater noise pollution has been rising due to increasingly more industrial and commercial activities. Shipping noise has doubled each decade since it was first measured in 1960, according to the nonprofit Ocean Conservancy. The disruptive cacophony can cause hearing loss, stress responses, changes in geographic range and disruptions in feeding and breeding in marine creatures.

“Anthropogenic noise has emerged in the ocean on human timescales, not evolutionary timescales,” Michelle Fournet, an acoustic ecologist at the University of New Hampshire who did not participate in the study, tells National Geographic. “So, the question this study begs is: ‘Do the changes [to codas] help the whale?’ Knowing that is the key to interpreting the results.”

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