Seal pups can change their vocal signals in response to environmental factors, an ability called vocal plasticity.

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To humans, baby seals are merely adorable mammals and assets to marine ecosystems, but we may have more in common with the cuddly creatures than you think. According to a new study published Monday in the journal Philosophical Transactions of The Royal Society B, baby seals have a rare trait seen among mammals: the ability to imitate sounds. "By looking at one of the few other mammals who may be capable of learning sounds, we can better understand how we, humans, acquire speech, and ultimately why we are such chatty animals," says Andrea Ravignani, the study's senior investigator.

Being able to adjust vocal signals in response to environmental changes is what's known as vocal plasticity, and it's a trait commonly used by humans. Being vocally plastic allows you to change the pitch of your voice to be better understood when communicating and it's a skill very few mammals possess. According to the study authors, being able to clearly and accurately communicate is important for mating opportunities, escaping from predators, and social learning. Researchers were particularly interested in studying this in baby seals because vocal learning is a trait previously seen among adult harbor seals. 

harbor seal pup on beach
Credit: lu-pics / Getty Images

To obtain their findings, the researchers studied eight harbor seal pups that were one to three weeks old. The seals were being held in a rehabilitation center in the Netherlands before being released back into the wild. To find whether or not the mammals are vocally plastic, the team started by recording noises from the nearby Wadden Sea. For several days the sea noises were played back to the seals in varying levels of loudness—from no sound to 65 decibels. They found the pups lowered their tone of voice when they heard louder sea levels and they kept a steady pitch with more intense noise levels.

One seal even produced louder calls when the noise got louder, a phenomenon known as the Lombard Effect. It's typically seen in human speech because people have the tendency to raise their voices in loud settings to be better understood. The results show that young seals adapt to the noises in their environment by lowering their tone—a trait they share with humans and bats. Other animals in similar experiments only raise their voice in response to louder noise. "Seal pups have a more advanced control over their vocalisations than assumed up until now", says Ravignani. "This control seems to be already present at only few weeks of age. This is astonishing, as few other mammals seem capable of that."

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