Monita Chatterjee, Ph.D., Director of Auditory Prostheses and Perception lab, recently co-authored an article published in Nature Scientific Reports. Dr. Chatterjee worked with collaborators in Canada, Taiwan and San Francisco to test children with cochlear implants on their ability to differentiate pitch inflections.
One downside of cochlear implants is that they don't adequately transmit pitch information, which can be problematic in languages where tone is crucial to comprehension.
In tone languages such as Mandarin Chinese, the lexical tone (pitch inflections within spoken syllables) can define a word. For example, the same word spoken with a rising or falling pitch might have very different meanings. Dr. Chatterjee's group set out to determine if native Mandarin-speaking children with cochlear implants have a greater sensitivity to changes in pitch compared to English-speaking children with cochlear implants. They hypothesized that immersion in a tone-language environment from birth would help the Mandarin-speaking children to process pitch changes better than English-speaking children in the US.
"Even for children who are implanted early, the adaptability of their brains to catch the differences in pitch is very limited," Dr. Chatterjee said. "It's a major device limitation."
Dr. Chatterjee and her collaborators tested 97 children in Taiwan and 97 children in the US on two pitch perception tasks. Each test group had both normal hearing children and children with cochlear implants.
"Compared to children speaking English in the US, children with normal hearing in Taiwan who speak Mandarin showed an advantage in both tasks," Dr. Chatterjee said. "Children with cochlear implants who spoke Mandarin showed large deficits in both tasks, which was expected, but even they showed the tone-language advantage in labeling the changes in pitch."
Results of the study have concluded that the demands of a tonal language have helped Mandarin-speaking children with cochlear implants develop a better ability to determine pitch changes. While their ability is limited and the sound quality is still highly degraded, the results suggest that the natural training provided by one's native language can substantially affect young brains' ability to perceive sounds.
The full report can be read here.
According to their website, Nature Scientific Reports is a weekly international publication for peer-reviewed research in scientific and technological fields. The research is published based on originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions.