Phonetics is concerned with the physical properties of speech. Listeners are sensitive to phonetic differences as part of what makes a person's voice unique. But individuals with dyslexia have trouble recognizing these phonetic differences, whether a person is speaking a familiar language or a foreign one.
Tyler Perrachione with the Massachusetts Institute of Technology (MIT) 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. It is remarkable that individuals with dyslexia are no better able to identify voices speaking a familiar language than a foreign one. It is also very interesting that the reason for this is that they are less accurate at voice recognition than individuals who don't have dyslexia."
For their research study, the MIT scientists trained individuals 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. In each language, participants learned to associate five talkers' voices with unique cartoon avatars and were subsequently tested on their ability to correctly identify those voices.
The listeners were either typically-developing readers or individuals who experienced reading difficulties and dyslexia growing up. Analyzing research found individuals with dyslexia were significantly worse at being able to consistently recognize the voices of the English speakers. 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.
Contemporary theories of dyslexia often propose a "phonological deficit" as the reason some people struggle to translate written images into meaningful language. The idea is that individuals with dyslexia tend to do poorly on tests that ask them to decode words using conventional phonetic rules, thereby resulting in reading delays because of difficulties connecting language sounds to letters.
"Our results are the first to explicitly link impairment in reading ability to impairment in ecologically processing spoken language. The results suggest that the source of a phonological deficit might be in dyslexic individuals' difficulties learning the consistent properties of speech sounds as spoken by an individual talker. Lots of research has shown that individuals with dyslexia have more trouble understanding speech when there is noise in the background. These results suggest that trouble following a specific voice might be part of the cause. Teachers and other educators can be sensitive to this during classroom instruction where noise from other classmates might make it disproportionately difficult for children with dyslexia to follow what is going on in a lesson."
If further research verifies this trouble noticing consistency, it might suggest a specific direction for slowing or stopping early speech and language difficulties for young children at risk of dyslexia.
Written by Sy Kraft