Dyslexia may impair voice recognition

WASHINGTON – Pick up the phone and hear, “Hey, what’s up?” Chances are, those few words are enough to recognize who’s speaking – perhaps unless you have dyslexia.

In a surprise discovery, researchers found adults with that reading disorder also have a hard time recognizing voices.

The work isn’t just a curiosity. It fits with research to uncover the building blocks of literacy and how they can go wrong. The eventual goal: To spot at-risk youngsters even before they open “Go, Dog, Go!” in kindergarten – instead of diagnosing dyslexia in a struggling second-grader.

“Everybody is interested in understanding the root cause of dyslexia, so we can intervene early and do something about it,” says Massachusetts Institute of Technology cognitive neuroscientist John Gabrieli, senior author of the study published last week in the journal Science.

Dyslexia is thought to affect 8 percent to 15 percent of Americans, who can have great difficulty reading and writing. It’s not a problem with intelligence or vision. Instead, it’s language-based. The brain struggles with what’s called “phonological processing” – being able to distinguish and manipulate sounds, like “bah” and “pah,” that eventually have to be linked to written letters and words.

A graduate student in Gabrieli’s lab wondered if dyslexia would impair voice recognition as well. After all, subtle differences in pronunciation help distinguish people.

Differences in brain-processing show up even in infants, says Patricia Kuhl of the University of Washington, who studies how babies learn language.

A colleague in her lab tested how well babies could distinguish “ah” and “ee” sounds between ages 7 months and 11 months. Those who did best wound up with bigger vocabularies and better pre-reading skills, such as rhyming, by their fifth birthdays. That doesn’t mean they’ll go on to experience dyslexia, but it does show how very early development can play a role in reading-readiness.

But Kuhl says the voice-recognition study has broader implications for brain science. It shows that for split-second recognition, the brain’s social-oriented right side works together with the speech-perception region of the left brain. People with dyslexia apparently are missing some of that interaction.