Professor Vincent Janik of the Scottish Oceans Institute (SOI) said the study of three young seals could be used as a new model to study speech disorders by providing a “better understanding of the evolution of vocal learning.”
The three seals – Zola, Gandalf and Janice – were first trained to mimic common seal sounds, before the pitch and tone were slowly shifted to replicate human-like speech. Their ability to learn the new sounds was analysed by monitoring for a shift in formants – sounds that determine the phonetic quality of a vowel and encode most the information in human speech.
Zola was particularly adept at mimicking melodies, replicating a series of notes from the nursery rhyme ‘Twinkle, Twinkle, Litter Star,’ while Gandalf and Janice were also taught to accurately reproduce combinations of human vowel sounds.
Lead researcher Dr Amanda Stansbury, now working at El Paso Zoo in Texas, said the study builds upon previous anecdotal evidence of how flexible seal vocalisations are.
Using seals as a test subject overcomes a significant ethical issue in studying humans, in that you cannot isolate a newborn from birth and control their aural environment. There is no such problem with seals pups, which are naturally separated from their mother two or three weeks after birth.
Professor Janik told Reuters in a telephone interview that there are enough physiological similarities between humans and seals to build a workable model for tackling speech disorders, which is surprisingly not possible with most nonhuman primates, whose abilities in this field are quite limited.
“You can test which sounds are learnt, and in what quantities and combinations,” Janik said. “You can then identify which sounds help slower learners to develop and use that as a blueprint for working with humans.”