The Chinese language baffles most foreigners and scientists have discovered it baffles the brain too.

The brain initially "mistakes" the lexical tone, or pitch of words, as music, and lets its right side dominate the cognitive processing of the tone, according to a latest study by Chinese scientists.

This "mistake" occurs about 200 milliseconds after the sound is picked up by the ear. After that flash moment, the left side of the brain takes over the control for processing the meaning carried by the tone, said the research report published last month by the Proceedings of the National Academy of Science, a premium US academic journal.

The finding suggests that Chinese may use their right brain more often than Westerners do while listening to their native tongue, according to Chen Lin, who led the research team.

The discovery might also help scientists develop more effective diagnostic and rehabilitation approaches for Chinese patients with lesions on the right side of the brain or deafness, he added.

Twenty-two young Chinese subjects, with no professional training in music, participated in the study carried out by Chen and his colleagues at the University of Science and Technology of China based in Hefei of East China's Anhui Province.

The subjects watched a silent movie while passively listening to, but not paying attention to, a string of Chinese words accented with various lexical tones.

"We recorded brain waves around 200 milliseconds after onset of the stimulus, when it is still too early for the stimulus sound to catch the brain's attention, and found stronger waves on the right side of the brain," Chen said.

He explained that the silent movie was used to deflect the subjects' attention away from the lexical tone stimulus.

"Our study has helped solve a dispute over what cues the human brain uses to determine the labor division of the two hemispheres," Chen noted.

The conventional wisdom since the 19th century has been that the left side of the brain dominates speech perception, while the right dominates music perception.

However, controversy remains over why the brain makes such a division of labor, and has given rise to two competing hypotheses.

One claims that it is because speech and music serve different functions while the other argues that it is because the two sounds have distinct acoustic properties.

With their research, Chen and his colleagues have been able to bring the two hypotheses into harmony by using Mandarin Chinese, a tonal language.

Mandarin is musical by nature. Each syllable in Chinese is pronounced in one of four lexical tones associated with different meanings. For example, the syllable "bai" can be accented in four tones to represent four different words that mean "split", "white", "swing" or "defeat".

In most Western languages such as English, changes in pitch, or intonations, indicate differences between a statement or a question, or of mood, but the meaning of the words remains unchanged.

"Our results show that both hypotheses hold," said Chen. "They just work at different stages of speech processing in the brain."

It means that immediately after the lexical tones of Mandarin are perceived by the brain, it is their acoustic features that the brain uses to decide where the lexical tone signals should go. Then quickly, the brain finds it has made a "mistake" the signals actually carry a meaning and so will correct itself and dispatch the signals to the left brain.

However, Chen said, it was still unclear whether these signals reached both hemispheres simultaneously before being dispatched, or were dispatched right upon arrival.

According to co-author Zeng Fan-Gang, the finding offers some clues as to why people who use auditory prosthetic devices have difficulty understanding Mandarin.

Zeng leads a hearing and speech laboratory at the University of California, Irvine for the development of cochlear implants.

Zeng and his colleagues have discovered that enhancing the detection of frequency modulation significantly boosts the performance of many hearing rehabilitation devices by increasing tonal recognition, which is essential to hearing music and understanding certain spoken languages, such as Mandarin.

(China Daily 01/08/2007 page8)