Human language

Like humans, baby seals can change the tone of their voice


A baby seal from the Seal Center Pieterburen.

John o’connor

When humans are babies, despite a vocabulary limited to “goo’s” and “gaa’s”, we send out thoughts and adapt to environmental sounds by adjusting the rate of our cooing. Scientists suggest that seal pups can also refine their adorable “arfs,” a rare feature for mammals outside of us.

After exposing eight seal pups to audio clips of the Wadden Sea with varying degrees of loudness, the researchers found that puppies intentionally lower their tone during more intense soundscapes instead of cranking it up to compete with the noise. The team published its findings Tuesday in the Philosophical Transactions journal of the Royal Society B Biological Sciences.

Although previous research has supported the ability of seals to imitate sounds, this study, according to the article, is the first observation of tonal alterations in slippery gray animals while they were still puppies.

“If seal pups acted like most animals, we would just expect them to increase the intensity of their voices as the noise increases,” said Andrea Ravignani, researcher at the Max Planck Institute for Psycholinguistics. . “However, the seals have lowered their voices to escape the frequency range of noise, which only animals with good control of their larynx – including humans but potentially excluding most mammals – can do. “

While it may seem contradictory that seal pups have lowered their voices in response to increased ambient sounds, this change indicates a active volume adjustment. This means that puppies have vocal plasticity or the ability to change the tone of the voice like humans.

Animals that do not change their tone tend to reflexively raise their voices in an attempt to combat loud noises, a phenomenon known as the Lombard effect. Humans also exhibit the Lombard effect when they argue with someone or talk in a chaotic environment.

Unlike animals that don’t change their tone, however, humans can dismiss the Lombard effect once they realize it’s happening and then pick a tone for the situation. Ravignani and his team have found baby seals doing just that.

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Baby seals tested for vocal plasticity

John o’connor

And if you were wondering why these sea puppies would choose to soften their tone amid a lot of noise, the paper offers some functional explanations. First, it suggests that the simulated soundscapes presented to the puppies reminded them of the sound of the wild wind.

Lower tones spread better in the wind, the paper says, helping sound travel greater distances. But the other reason the team (and my favorite) is that the baby seals fell in lower tones as a way to express themselves and showcase their individuality.

The researchers note, however, that a baby seal was an anomaly. He raised his voice according to the Lombard effect when exposed to a louder sound, while the others lowered theirs. “Based on these results,” the paper says, “we cannot rule out that seal pups may increase the amplitude of their voices in response to noise.

Sounds of baby seals could help language studies

For an animal to have vocal plasticity, its brain must somehow communicate with the body’s voice-producing center, or the larynx, according to Ravisnani and his fellow researchers.

“The human ability to speak and sing relies on our exquisite control of the vocal organs,” Ravignani said. “Especially our larynx and vocal cords. If you put your hand to your throat and say ‘a’, the vibration you feel is that your vocal cords vibrate about 100 times per second. Without our developed control for sound production, the spoken language – including learning new sounds during infancy – would be impossible. “

Adding that, “Seals may be one of the very few mammals which, like humans, when singing or speaking a tonal language, can flexibly modulate the pitch of their voice.” Studying how seals adjust their tones could help solve the mystery of human speech patterns.

Of course, we know that our infantile gibberish turns into real words, which then turn into cohesive sentences and structured, structured ideas. But how all evolution occurs is still open to debate.

“By finding another mammal capable of modulating the pitch of its voice, we can begin to build an evolutionary tree of speech building blocks and show that some of them are in fact not uniquely human,” Ravignani said. . “To show that a baby seal does, spontaneously and without training, what our closest living relatives – chimpanzees – cannot do even after years of training is quite striking.”


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