Tyler Perrachione, a doctoral candidate at the Massachusetts Institute of Technology, says even though all people who speak a language use the same words, they say those words just a little bit differently from one another -- what is called phonetics in linguistics.
Listeners are sensitive to phonetic differences as part of what makes a person's voice unique, but individuals with dyslexia have trouble recognizing phonetic differences, whether a person is speaking a familiar language or a foreign one, Perrachione says.
The MIT scientists trained people with and without dyslexia to recognize the voices of people speaking either the listeners' native language of English or an unfamiliar foreign language, Mandarin Chinese.
The neuroscientists found people with dyslexia were significantly worse at being able to consistently recognize the voices of the English speakers, but they were about the same as listeners without dyslexia at recognizing the Chinese voices. Both groups were very poor at recognizing voices speaking an unfamiliar language, Perrachione says.
The finding, published in Science, reaffirms the theory that the underlying deficit in dyslexia isn't about the act of reading per se, but instead involves difficulty with how sounds of spoken language are heard and processed in the dyslexic brain.