For a long time, scientists assumed that sperm whale (Physeter macrocephalus) calls consisted solely of rapid clicks – a style of underwater Morse code.
These “codes,” or sequences of clicks, that whales use to speak seemed quite easy in comparison with human speech.
However, recent study highlighted by National Geographic suggests that there’s a hidden sophistication beneath these clicks: elements of whale vocalizations are strikingly much like human vowels.
How researchers discovered the pattern
The discovery is the results of the CETI (Cetacean Translation Initiative) project, a collaborative effort combining linguistics, marine biology, artificial intelligence and acoustic evaluation.
The team – including linguists from the University of California, Berkeley – analyzed greater than a thousand code recordings collected from sperm whales near Dominica within the Caribbean.
Using a custom machine learning model, they first flagged vocalizations of interest after which examined them intimately.
When the sequences were sped up (removing the silence between clicks and shortening the time), previously hidden tonal features emerged – features that resembled the sustained tones of human vowels.
The study identified two distinct vowel-like patterns in multiple codas, labeled “a-coda” and “i-coda”, roughly analogous to the vowels “a” and “i” in human speech.
Additionally, some codes were characterised by diphthong-like patterns – smooth transitions from one vowel quality to a different – very like humans mix vowels into diphthongs.
What this implies for understanding how whales communicate
These findings challenge the long-held view that whale clicks are purely binary mechanical signals. Instead, the presence of vowel- and diphthong-like features dramatically expands the expressive potential of sperm whale vocalizations.
The whales’ ability to modulate pitch, pitch and duration suggests that the vocal system is rather more flexible and nuanced than previously thought – perhaps closer to the fundamental elements of human speech than to easy animal calls.
This discovery builds on previous research conducted by the CETI Project, which has already identified a growing “phonetic alphabet” of codes, increasing the known repertoire from several dozen basic patterns to over 150 distinct code types by analyzing differences in rhythm, tempo and timing.
The addition of vowel-like spectral patterns adds a brand new layer of complexity that will enable more sophisticated 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, although different, functionally resemble the human sound-shaping mechanism.
By manipulating air and tissue internally, whales appear to find a way to shape click sequences into vowel-like tones.
This convergent evolution – different anatomy, similar vocal effects – highlights that complex communication is probably not unique to humans.
It suggests that, given the proper biological and social pressures, other species can evolve systems that match our own language-building tools.
What does this research result in?
Despite this step forward, researchers emphasize that they’ve not yet deciphered the meaning of any specific code or sequence.
At this point, the work reveals structural and phonetic complexity, but not semantics. In other words: we all know that sperm whales can have “vowels”, but we don’t yet understand what “words” they’ll form or what “sentences” they’ll convey.
To move from structure to meaning, scientists will need rather more data — not only acoustic recordings, but in addition detailed observations of whale behavior and the context through which the codes are used.
Only then will it’s possible to associate specific sounds with specific actions, intentions or emotions.
Meanwhile, this amazing discovery is already encouraging us to reconsider assumptions about animal communication.
Sperm whales – massive, slow-moving creatures that inhabit a world very different from ours – may share a basic ability with humans: constructing sounds based on a “phonetic alphabet.”
They may find a way to shape them into distinct “vowels” and mix them into structured, potentially meaningful sequences.
It’s a profound reminder that the road between human language and animal communication could also be much thinner than once thought.
