Whistled Turkish: 'True experiment of nature' where language is adapted to both sides of brain

Scientists have discovered a language called whistled Turkish utilises both sides of the brain – an exception to the rule that language is a processed by the left hemisphere. The team of researchers made the discovery while examining the brain asymmetry in processing spoken Turkish versus whistled, finding the latter produced a "balanced contribution of the hemispheres".

Whistled Turkish is speech that has been adapted into a series of whistles. It was developed long ago, before the introduction of telephones, in small villages in Turkey so people could communicate over long distances. This is because it carries much further, so people could be heard far away across canyons and mountains. Normally, they would use spoken language at close range, then switch to whistling from around 50m.

Onur Gunturkun, of Ruhr-University Bochum in Germany, explained whistled Turkish is not a distinct language, instead it is just converted into a different form – just like how reading this article is a written conversation of the English language. However, most of the time language is processed by the brain's left hemisphere, be it written, spoken or signed.

"We are unbelievably lucky that such a language indeed exists," Gunturkun said. "It is a true experiment of nature. If you look at the topography, it is clear how handy whistled communication is. You can't articulate as loud as you can whistle, so whistled language can be heard kilometres away across steep canyons and high mountains."

He said it provided an ideal opportunity to test the idea that the language is predominantly an activity for the brain's left hemisphere. Auditory processing of features, such as pitch, melody and frequency, is processed by the right side.

The scientists, publishing their findings in the Cell Press journal Current Biology, presented whistled Turkish speakers with headphones, with speech sounds (both spoken and whistled) delivered to their left or right ears through headphones. After reporting what they heard, findings showed participants perceived spoken language in the right ear (sounds to the right ear go to the left hemisphere first, while through the left ear go to the right hemisphere first then passed on to the left), but they heard whistled sounds equally well through both ears.

"We could show that whistled Turkish creates a balanced contribution of the hemispheres," Gunturkun explained. "The left hemisphere is involved since whistled Turkish is a language, but the right hemisphere is equally involved since for this strange language all auditory specialisations of this hemisphere are needed." The team now plans to conduct EEG studies to look at the brain processes involved in whistled Turkish.