Imagine getting up for breakfast, saying a bleary “Good morning” and hearing someone else’s voice coming out of your mouth. A Plymouth resident experienced just such a jolt to her identity in 2010.
She was hospitalised after a severe migraine, and suffered an unusual complication, apparently similar to a stroke. Like many stroke patients, her language was affected. What made this woman’s case so striking was the change in her accent, which sounded Chinese to many listeners.

As seen in a recent BBC documentary (“The Woman Who Woke Up Chinese”), “foreign accent syndrome” is very rare, but can have profound personal consequences. Notoriously, a Norwegian woman, Astrid L., was left with a strong German accent after suffering head injuries during an air-raid in 1941. Speaking in apparent imitation of the wartime enemy, she was ostracised by friends, despite having no control over her accent.

Our power of voice is fundamental to our identity. Perhaps the most important lesson from these “foreign accent” cases is that our sense of self is strongly affected by our spoken interactions with other people. The foreign accent is, in fact, as much in the ears of the listener as the mouth of the sufferer.

Why are we so sensitive to differences in how people speak? One theory of the origin of human language may provide a clue. Chimpanzees, our nearest relatives, maintain good social relations by mutual grooming sessions, smartening up each other’s fur by stroking and picking off twigs and insects. This promotes trust between chimpanzees who rely on each other for help with hunting and foraging for food, and crucially, for defence from other groups of their fellow creatures. As early humans moved out of the forests and onto the African plains, our social groups became larger than those of our primate cousins. This made it impossible to devote hands-on grooming time to all group members. Instead, the theory suggests, we started using vocal signals to indicate our loyalties. The giant leap towards human language may have been given a crucial push by the need to prove trustworthiness within our early stone-age tribes.

Of course, speech can only be a reliable signal of potential cooperation or conflict if we are sensitive to differences between voices. Research on very young infants suggests that we are born with this ability already active, if not fully developed. Growth in the womb takes place to a lively soundtrack of internal sounds – breathing, heart-beats, tummy rumbles – together with all the sounds of the outside world that the mother hears, though perhaps a little muffled. The mother’s voice is loud and clear to the developing foetus, however. Not surprisingly, new-born babies prefer their mother’s voice to another woman’s, the first sign of the lifelong human tendency to judge people by their accents.

The Babylab at Plymouth University is one of Britain’s leading centres researching the development of language skills, from just after birth to six years old and beyond. “Babies react differently to familiar and new sounds,” says Dr Caroline Floccia, head of the Babylab. “By monitoring where babies look when listening to sounds and accompanying visual stimuli, we can work out whether they can tell different accents and languages apart.”

In one recent project, local babies at five months old, sitting comfortably on their carer’s knee, were able to hear the difference between a Plymouth accent and a Welsh accent, but – rather surprisingly – could not tell Plymouthian and French speakers of English apart. When played sentences from other languages, babies could clearly distinguish French and Spanish, but not Spanish and Finnish.

“The fact that babies can discriminate some accents and languages, but not others, tells us about the features of speech that are really important for them,” says Dr Floccia. Analysis of these babies’ behaviour suggests that they are sensitive to small differences in the duration of certain sounds, barely noticeable signs in speech that tell listeners when sentences are about to finish. As they say about comedy, the answer may lie in the timing.

If you are interested in contributing to research on language development and have a child aged 0 to 6 years, please contact us at the Plymouth Babylab on 01752 584865 or visit www.plymouthbabylab.org.

[This article first appeared in the Plymouth Magazine in October 2013.]