Research conducted by specialists from the USA and Hong Kong has revealed phonological patterns in the acoustic signals of sperm whales that are similar to those found in human languages. It was discovered that these marine mammals use analogues of vowel sounds, adjust their duration, and modify their acoustic qualities depending on neighboring signals during communication. This finding points to a high level of complexity in the sperm whale communication system among animals.

Features of Sperm Whale Communication

Sperm whales (Physeter macrocephalus) communicate underwater using short series of clicks known as codas. Previously, biologists classified these signals by rhythm and tempo; for example, the "1+1+3" coda indicates two slow clicks followed by three rapid ones. Recent studies have shown that the clicks themselves have different acoustic characteristics (formants), similar to vowel sounds in human speech. Signals with a single frequency peak were conditionally called "a-codas," while those with two peaks were called "i-codas." This raised the question of whether these sounds are random physiological phenomena or if sperm whales consciously combine them according to specific rules.

Research Methods

The analysis used data from the CETI (Cetacean Translation Initiative) project, which includes recordings of Caribbean sperm whales collected from 2014 to 2018 using special suction-cup microphones (DTAGs) attached to the animals' backs. This allowed researchers to isolate the sounds of individual whales from ocean background noise and signals from other pod members. Linguists, both manually and with the help of artificial intelligence algorithms, filtered 1,144 codas recorded from 15 different whales.

Similarities with Human Phonetics

The analysis showed that the acoustic system of sperm whales in many ways resembles human phonetics. Five key parallels were identified:

1. Control of sound duration: Sperm whales consciously regulate the length of their sounds. For example, the "i" sound in their codas can be short or long, similar to how vowel length can change word meaning in languages like English or Finnish.
2. Differences in coda duration: The basic length of "a-codas" is systematically longer than that of "i-codas," which aligns with universal phonetic rules—producing the "a" sound generally takes more time.
3. Coarticulation effect: Researchers observed the phenomenon of sound blending, where the first click in a coda changes its tone depending on the preceding signal, much like how articulation in human speech is influenced by neighboring sounds.
4. Independent combination of rhythm and timbre: Sperm whales can independently combine rhythmic patterns and acoustic coloring, comparable to tonal languages where changes in intonation alter word meaning.
5. Association of vowels with rhythms: Certain "vowel" sounds are statistically more often used with specific rhythms, a pattern also seen in human languages.

Individual Characteristics

Each sperm whale was found to have unique vocal features, such as a characteristic tempo. For example, one female produced signals on average 15% slower than another individual.

Significance of the Study

The results show that complex phonology—the integration and modulation of sounds—is not a uniquely human achievement. Despite the evolutionary paths of humans and toothed whales diverging tens of millions of years ago, sperm whales have independently developed a communication system that mathematically and structurally mirrors the principles of human linguistics.