For decades, scientists assumed that the voices of Sperm whale (Physeter macrocephalus) consisted solely of rapid clicks — a kind of underwater Morse code.
These “codas,” sequences of clicks that whales use to communicate, seemed rather simplistic compared to human speech.
However, a new study highlighted by National Geographic suggests that beneath those clicks lies a hidden sophistication: elements of the whales’ vocalizations bear striking resemblance to human vowels.
How Researchers Uncovered the Pattern
The discovery stems from work by Project CETI (Cetacean Translation Initiative), a collaborative effort combining linguistics, marine biology, artificial intelligence, and acoustic analysis.
The team — including linguists from University of California, Berkeley — analyzed over a thousand recordings of codas collected from sperm whales near Dominica in the Caribbean.
Using a custom machine-learning model, they first flagged interesting vocalizations and then examined them in close detail.
When the sequences were sped up (removing silence between clicks and compressing time), previously hidden tonal qualities emerged — qualities that resembled the sustained tones of human vowels.
The study identified two distinct vowel-like patterns across many codas, labeled as “a-coda” and “i-coda,” roughly analogous to the vowels “a” and “i” in human speech.
Additionally, some codas featured diphthong-like patterns — gliding transitions from one vowel quality to another — similar to how humans combine vowels in diphthongs.
What This Means in Understanding How Whales Communicate
These findings challenge the long-held view of whale clicks as purely binary, mechanical signals. Instead, the presence of vowel-like and diphthong-like qualities dramatically expands the expressive potential of sperm whale vocalizations.
The whales’ capability to modulate pitch, tone, and duration suggests a vocal system far more flexible and nuanced than previously thought — perhaps closer to rudimentary elements of human speech than to simple animal calls.
This discovery builds on earlier research from Project CETI, which had already identified a growing “phonetic alphabet” of codas, increasing the known repertoire from a few dozen basic patterns to over 150 distinct coda types by analyzing variations in rhythm, tempo, and timing.
The addition of vowel-like spectral patterns adds a new layer of complexity that could enable more refined communication.
Anatomical Mechanism
Interestingly, whales don’t use vocal cords like humans. Instead, sperm whales produce sounds using “phonic lips” and an air sac — anatomical structures that, while different, functionally resemble the human mechanism for shaping sound.
By manipulating air and tissue internally, whales appear capable of shaping their click sequences into vowel-like tones.
This convergent evolution — different anatomy, similar vocal effects — underscores that complex communication may not be unique to humans.
It suggests that under the right biological and social pressures, other species may evolve systems that parallel our own language-building tools.
What This Research Leads
Despite this leap forward, researchers emphasize that they have not yet decoded the meaning of any specific coda or sequence.
At this point, the work reveals structural and phonetic complexity, but not semantics. In other words: we know sperm whales may have “vowels,” but we don’t yet understand what “words” they might be forming, or what “sentences” they may convey.
To move from structure to meaning, scientists will need much more data — not only acoustic recordings, but also careful observations of whale behavior and context when codas are used.
Only then may it be possible to associate specific sounds with specific actions, intentions, or emotions.
Meanwhile, the amazing discovery already invites us to reconsider assumptions about animal communication.
Sperm whales — massive, slow-moving creatures that inhabit a world utterly different from ours — may share with humans a fundamental capacity: building sounds from a “phonetic alphabet.”
They may be able to shape them into distinct “vowels,” and combining them into structured, potentially meaningful sequences.
It is a profound reminder that the boundary between human language and animal communication may be far thinner than we once believed.
