A Massachusetts Institute of Technology study suggests that dyslexia may be a hearing problem as well as a visual impairment.
The ability to recognize voices is something most people take for granted. However, for individuals with dyslexia, voice recognition may also be impaired, a study from the Massachusetts Institute of Technology suggests.
The study, “Human Voice Recognition Depends on Language Ability,” was published in the July issue of the journal Science. Researchers on the study suggest that phonology—the ability to process the relationship of sounds and meanings—may be impaired in people with dyslexia, making it more difficult for these individuals to identify people speaking in their native language. Researchers also found that people with dyslexia had as difficult a time recognizing voices of people speaking in their native language as they did when listening to speakers of a foreign language. According to John Gabrieli, MIT’s Grover Hermann Professor of Health Sciences and Technology and Cognitive Neuroscience and senior author of the Science paper, the outcome supports the idea that impaired phonology processing is a critical aspect of dyslexia.
“Recognizing one person from another, in humans, seems to be very dependent on human language capability,” said Gabrieli.
Lead author of the study, MIT graduate student Tyler Perrachione, said that the way people speak individual words is important for voice recognition.
“Everybody’s speech is a little bit different, and that’s a big cue to who you are,” he said. “When you’re listening to somebody talk, it’s not just properties of their vocal cords or how sound resonates in their oral cavity that distinguishes them, but also the way they pronounce the words.”
Perrachione and Gabrieli worked together, testing subjects who attempted to identify people speaking in their native language (English) and then Chinese. What they found was that non-dyslexic participants were correct almost 70 percent of the time when listening to people speaking in English, and only 50 percent when those same participants spoke in Chinese. Dyslexic individuals, however, only recognized 50 percent, regardless of language. This suggests that people with dyslexia may have trouble following speakers, adding to mounting evidence that dyslexia is more than a visual impairment.
“There was a big shift in the 1980s from understanding dyslexia as a visual problem to understanding it as a language problem,” Gabrieli explained. “Dyslexia may not be one thing. It may be a variety of ways in which you end up struggling to learn to read. But the single best understood one is a weakness in the processing of language sounds.”
To help determine which areas of the brain are most active during voice identification in both dyslexics and non-dyslexics, researchers are currently using functional magnetic resonance imaging.
Researchers also indicated that the study results may help shed light onto the performance of computerized voice-recognition systems, helping them do a better job of understanding different sounds made by different speakers.
“It’s a beautiful study, in the sense that it’s so simple,” says Shirley Fecteau, a visiting assistant professor at Harvard Medical School and research chair in cognitive neuroplasticity at Laval University in Quebec. “It really seems like a very clear effect on voice recognition in people with dyslexia.”
The complete study is available at the Science journal website.
How can I overcome Dyslexia at 52 years old?