Humans and baby seals both have the ability to change the tone of their voices.
Seals have the unusual capacity among mammals to adjust their voice tone to replicate human speech, sparking a study that could shed light on how humans learn to communicate.
“By looking at one of the few other mammals that may be capable of learning sounds, we can better understand how we, humans, acquire speech and, ultimately, why we are such chatty animals,” Andrea Ravignani, lead researcher in the study published in the Philosophical Transactions of the Royal Society B Biological Sciences, said.
Researchers at the Seal Rehabilitation and Research Centre in Pieterburen, The Netherlands, studied eight harbor seal pups ranging in age from one to three weeks to learn how seals change their voices to sounds in their environment.
Seal pups that had been tested were placed in quarantine units with all sound coming from recordings. To avoid the sounds of running water, there was no water in the pool.
Over the course of several days, the seals were exposed to recordings of the neighboring Wadden Sea on the Dutch coast, which were played at three different noise levels ranging from 0 to 65 decibels, but with a tone that resembled the seal pups’ natural sounds. The puppies’ spontaneous calls were also recorded by the research team.
The researchers discovered that when the young seals were exposed to stronger sea noises, their tone of voice dropped and their pitch remained constant. When the sea sounds became stronger, one of the pups displayed the so-called Lombard effect, emitting louder calls. When the pups were exposed to varied amounts of sea noise, they did not make more or longer sounds.
To be heard in a noisy environment, humans and many other animals raise their voices louder, but only a few mammals can change their pitch.
The researchers discovered that young seals, like bats and humans, adapt to their aural environment by reducing their tone. Other animals in identical studies just increased their volume when confronted with stronger sounds.
“Seal pups have a higher level of control over their vocalizations than previously thought,” Ravignani explained. Given how few animals are capable of such control at such a young age, he described it as “astonishing.” Humans are the only mammals with direct neural connections. This is a condensed version of the information.