[Animals] Scientists say they discovered a “phonetic alphabet” in the songs of sperm whales

[Noticias ALEJANDRO]

 

Scientists achieved a feat. They identified a previously unknown complexity in sperm whale communication after analyzing thousands of recorded sequences of sperm whale sounds with artificial intelligence.

Variations in tempo, rhythm and length of sequences of these sperm whale sounds, called codas, weave a rich acoustic tapestry. These variables suggest that sperm whales can combine patterns in multiple ways, mixing and matching phrases to convey a wide range of information to each other.
What sperm whales say is still a mystery to human ears. Still, uncovering the extent of sperm whales' vocal exchanges is an important step toward linking sperm whale calls to specific messages or social behaviors, the scientists reported May 7 in the journal Nature Communications.
“This work builds on many previous works focused on understanding sperm whale calls. However, this is the first work that began to analyze sperm whale calls in their broader communicative context and in the context of exchanges between sperm whales, which made some of the findings possible," said study co-author Dr. Daniela Rus, director of the Computer Science and Artificial Intelligence Laboratory (CSAIL) at MIT, in an email.

"Understanding what aspects of their codas they can control and vary helps us understand how they can encode information in their calls," Rus said.
The researchers called their catalog of sound combinations a "phonetic alphabet" for sperm whales, and compared variations in sperm whale click sequences with the production of different phonetic sounds in human speech.

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But while the team's findings are interesting, that term offers a misleading perspective on the vocal interactions of sperm whales, Dr. Luke Rendell, a researcher at the University of St. Andrews in the United Kingdom whose work is published, said in an email. focuses on communication in marine mammals.
"The presentation of the 'phonetic alphabet' is nothing like that," said Rendell, who was not involved in the research.

"The way tempo variation is used is completely different from how, for example, we use elements of an alphabet to construct a linguistic expression," he said. "There's no evidence for that, and it's not a very useful interpretation because it forces everything into a narrow and somewhat exaggerated view of 'it's like human language or it's not,' when there's a much wider range of interpretations available."

Pattern recognition
Sperm whales produce these sounds by forcing air through an organ in their heads called spermaceti, and these sounds can be as loud as 230 decibels, louder than a rocket launch and capable of rupturing human eardrums, another previously reported. team of scientists in the magazine Scientific Reports.

For the new study, researchers used machine learning to detect patterns in audio data collected by The Dominica Sperm Whale Project, a repository of observations of sperm whales living in the Caribbean Sea. The recordings represented the voices of approximately 60 sperm whales (a subset of a group of about 400 sperm whales known as the Eastern Caribbean clan) and the vocalizations were recorded between 2005 and 2018.

Previous research identified 150 types of codas in sperm whales around the world, but Caribbean sperm whales used only 21 of those codas.
The scientists examined the timing and frequency of 8,719 coda sequences: in solitary utterances by sperm whales, in choruses, and in call-and-response exchanges between sperm whales. When visualized with artificial intelligence, never-before-seen coda patterns emerged.

The authors of the study defined four variables in the codas: rhythm, tempo, rubato and ornamentation. Rhythm describes the sequence of intervals between those sounds. The tempo is the duration of the entire coda. Rubato refers to variations in duration between adjacent codas of the same rhythm and tempo. And ornamentation is an “extra click” added to the end of a coda in a group of shorter codas, Rus explained.
These so-called ornamental clicks "occur more toward the beginning and end of turns" during vocal exchanges between sperm whales, and "behave as speech markers," Rus said.

The discovery that sperm whales could synchronize variations in coda tempo was "a really interesting observation," Rendell said.

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