Sperm Whale Clicks Show Vowel-Like Spectral Structures, Study Finds

A scientific announcement on November 12, 2025, detailed the discovery of spectral patterns within sperm whale communication that closely resemble the vowels and diphthongs found in human speech. This research, a joint effort by the nonprofit Project CETI and the University of California, Berkeley, challenges the long-standing assumption that whale codas—sequences of clicks produced by the animals' phonic lips—functioned solely on a timing-and-count system analogous to Morse code.

The study focused on the acoustic properties of these codas, identifying two recurrent, distinct patterns across various individual whales: designated as the a-coda vowel and the i-coda vowel. These units appear to be actively exchanged during structured conversational exchanges. Furthermore, the research documented several 'diphthongal' patterns, which in human phonetics involve blending two vowel sounds, observed in the whales as rising, falling, or combined frequency shifts.

Gašper Beguš, Linguistics Lead for Project CETI and an Associate Professor of Linguistics at UC Berkeley, highlighted the linguistic significance of this resemblance to human vowel systems. A key methodological advance involved adjusting for the inherent timing differences between species; because sperm whale codas are generated by much slower phonic lips than human vocal folds, initial temporal variations obscured the underlying spectral structure. Once the timing variable was accounted for, the spectral patterns resolved sufficiently for transcription using conventional human alphabetical representations.

David Gruber, Founder and President of Project CETI, framed the findings as evidence that sperm whales have developed "an entirely independent way of producing vowels," underscoring the evolutionary divergence in their vocal apparatus. Project CETI, which began in 2020 with support from the TED Audacious Prize, utilizes advanced machine learning and robotics to decode sperm whale language. The primary field research site is located off the coast of Dominica in the Eastern Caribbean, chosen for its deep waters and stable resident whale population.

The interdisciplinary team, comprising over 50 scientists from fields including robotics, cryptology, and marine biology, aims to construct the first blueprint of another animal's language. While the discovery suggests a complexity approaching human language, external analysis, such as that from marine biologist Luke Rendell of the University of St. Andrews, has urged caution, suggesting the patterns could represent recording artifacts rather than intentional signals. The research is slated for publication in Open Mind on November 12, 2025, opening a new dimension in bioacoustics.