Hoover the seal was initially kept successful a household location and could imitate quality speech, barking drawback phrases successful a gruff accent ("Come implicit here"). But vocal learning -- the quality to imitate sounds -- is simply a uncommon trait among mammals. Only a fewer taxon whitethorn beryllium susceptible of changing the transportation of their dependable to dependable higher oregon lower, which is simply a important constituent of quality speech. "By looking astatine 1 of the fewer different mammals who whitethorn beryllium susceptible of learning sounds, we tin amended recognize however we, humans, get speech, and yet wherefore we are specified chatty animals," explains MPI's Andrea Ravignani, elder researcher of the study. Are seal pups already susceptible of changing the transportation (or 'tone height') of their voices?
Wadden Sea noises
The researchers studied 8 harbour seal pups -- 1 to 3 weeks aged -- that were being held successful a rehabilitation centre (the Dutch Sealcentre Pieterburen) earlier being released backmost into the wild. To analyse whether the pups could accommodate their voices to noises successful the environment, the squad archetypal recorded noises from the adjacent Wadden Sea. For respective days, the oversea noises were past played backmost to the pups, successful 3 degrees of loudness (varying from nary dependable to 65 decibel), but with a akin code tallness to that of the seal pups' calls. The squad besides recorded the pups' spontaneous calls. Would the pups alteration their code of dependable to accommodate to the oversea noises?
When the seal pups heard louder oversea noises, they lowered their code of voice. The pups besides kept a much dependable transportation with the much aggravated sound levels. One seal intelligibly showed the alleged Lombard effect, producing louder calls erstwhile the sound got louder. The Lombard effect is emblematic for quality speech, arsenic radical rise their voices successful sound to beryllium amended understood. The pups did not nutrient much oregon longer calls erstwhile they heard antithetic levels of oversea noise.
Direct neural connections
Apparently, young seals accommodate to the noises successful their situation by lowering the code of their voice, an quality they look to stock with humans and bats. Other animals successful akin experiments lone rise their dependable (i.e. marque louder calls) successful effect to louder noise.
"Seal pups person a much precocious power implicit their vocalisations than assumed up until now," says Ravignani. "This power seems to beryllium already contiguous astatine lone fewer weeks of age. This is astonishing, arsenic fewer different mammals look susceptible of that. To date, humans look to beryllium the lone mammals with nonstop neural connections betwixt the cortex ('the outer furniture of the brain') and the larynx ('what we usage to nutrient code of voice')," helium concludes. "These results amusement that seals whitethorn beryllium the astir promising taxon to find these nonstop connections, and unravel the enigma of speech."
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Materials provided by Max Planck Institute for Psycholinguistics. Note: Content whitethorn beryllium edited for benignant and length.
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