Scientists Discover Vowel- and Diphthong-like Patterns in Sperm Whale Communication

New research reveals a previously unknown dimension of sperm whale vocalizations, shedding light on their complex communication system.

NEW YORK, Nov. 12, 2025 /PRNewswire/ -- A groundbreaking study led by Project CETI (Cetacean Translation Initiative) and the University of California, Berkeley, has uncovered a new dimension of sperm whale communication, revealing spectral patterns analogous to human vowels and diphthongs. This discovery offers crucial insights into how whales may structure and transmit meaning, deepening our understanding of non-human intelligence.

This new study reveals that two discrete coda-level patterns appear across individual sperm whales: the a-coda vowel and i-coda vowel. Whales exchange these vowels in structured conversation and both coda vowels are possible on different traditional coda types, which increases the complexity of this communication system. In addition to vowels, the paper reports several "diphthongal" patterns. In human language, diphthongs are combinations of two vowels (such as o+u in "soul"). In sperm whales, we observe rising, falling and a combination of the two frequencies. This suggests that whale "coda vowels" are likely actively controlled by whales.

The research will be published in Open Mind on November 12, 2025.

A crucial step in the discovery was to change the human-biased perception of timing. Human vowels are produced by vocal folds which vibrate fast. Sperm whale codas are produced by phonic lips which are much slower. Once timing is removed, the patterns become so clear that we can transcribe them with human letters.

These findings challenge previous assumptions about sperm whale vocalizations and suggest that their communication system is far more intricate than previously understood. The ability to control properties in a structured way hints at the potential for sperm whales to encode additional layers of meaning, much like humans do in our speech.

By uncovering these complex vocal structures, this research marks a crucial step in deciphering the meaning behind sperm whale communication. Also, better understanding how elements of human-like communication, such as vowels, emerge in nature offers valuable insights into the evolution of intelligence and language across species.

Sperm whale codas—structured sequences of clicks used for communication—have traditionally been analyzed based on the number of clicks and their inter-click timing; a view that was recently widened with CETI's 2024 study of the "sperm whale phonetic alphabet." However, this new research demonstrates that sperm whales also modulate the frequency of their clicks, adding a previously unrecognized layer of complexity to their communication system and showing that their vocalizations are analogous to human vowels and diphthongs.

"What's interesting from a linguistics standpoint is the resemblance to human vowel systems. The presence of consistent vowel- and diphthong-like patterns points to a level of phonetic complexity previously thought to be unique to humans," shared Gašper Beguš, Project CETI's Linguistics Lead. "This is a step toward understanding whether the building blocks of language are more universal across species than we believed."

"This discovery opens an entirely new chapter in our understanding of sperm whale communication. By integrating linguistics and non-human communication, we are now aware that sperm whales have vowel- and diphthong-like structures in their voices, and that they evolved an entirely independent way of producing vowels." said David Gruber, Founder and President of Project CETI.

About Project CETI
Project CETI  (Cetacean Translation Initiative) is a nonprofit organization applying advanced machine learning and state-of-the-art robotics to listen to and translate the communication of sperm whales in the Eastern Caribbean off the coast of the island of Dominica. Its science team comprises leading artificial intelligence, natural language processing and complex systems experts, cryptographers, linguists, marine biologists, roboticists, engineers, and underwater acousticians in partnership between over 15 academic institutions and companies across six countries. In 2022, it published in iScience its scientific roadmap for advancing the understanding of sperm whale communication. This peer-reviewed academic paper outlines the key elements required for the collection and processing of massive datasets, detecting basic communication units and language-like higher-level structures, and validating models through interactive playback experiments. All of Project CETI's publications can be found here.

SOURCE Project CETI