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Auditory processing disorder

Does Auditory Processing Disorder Cause Dyslexia?

By Guinevere Eden

My son has auditory processing disorder. I’ve heard that APD is often the cause of dyslexia. Is this true?



Guinevere Eden

Director, Center for the Study of Learning, Georgetown University Medical Center

If you were to pose this question to a group of brain researchers, it would spark a lively debate. That’s because scientists don’t know yet what causes dyslexia.

Dyslexia is thought to have a biological basis, involving changes in the brain. Genes are also thought to play a role.

But the exact mechanism—and whether it involves auditory processing or not—is currently under intense investigation.

Researchers for most part agree on a critical problem that occurs with dyslexia. That is difficulty understanding the way words are made up of sounds (phonemes) and how these sounds are mapped onto their written counterparts (graphemes).

But the big debate is about when this problem occurs. Does it happen early on, in the “lower-level” processing of sounds? Or during “higher-level” processing that occurs in the realm of language and thinking?

Auditory processing disorder (APD) involves the processing of sounds. The question: Does dyslexia start there, too?

To help you follow the debate, here’s what happens when a person hears the word “understood.” The sounds that enter the ear are turned into signals that are transmitted from the inner ear to structures deep within the brain.

Next, the signals move to a part of the brain called the auditory cortex. And then they travel to other parts of the cortex that are responsible for “higher-level” functions, such as getting meaning from hearing “understood.”

Higher-level functions are also needed when the word is presented in print. Reading involves mapping the letters in the word to the corresponding sounds that are then pronounced as “understood.”

Scientists don’t yet know where in the process reading problems begin. But they are finding evidence of differences in the way people with dyslexia process auditory information.

These differences can be detected soon after the information enters the brain. They can also be seen at the level of the cortex that analyzes language and at various points in between.

It’s a chicken-and-egg problem. Does a person with dyslexia run into trouble at the higher-function level after passing through the lower level?

Or are the higher-level functions getting compromised because earlier parts of the auditory pathway aren’t sending along the correct signal?

It will be interesting to see where the science leads us. But in the meantime, I want to answer your question from a practical perspective: What does your son’s APD diagnosis mean for his reading skills?

Kids with APD are often at risk of having trouble with reading. That’s because they may not have clear and consistent access to the stream of sounds that are used in spoken language. This makes it difficult for them to build accurate representations in their mind of those sounds and then map them onto the text.

For example, if someone says “bring,” your son might hear “ring.” This will make it hard for him to understand why somebody is asking him to ring his shoes. 

This can also make it hard for him to sound out words he sees. Decoding is one of the essential skills needed for accurate reading. It can also impact reading comprehension.

It would be good to help your son improve his understanding of the sounds that make up our language. Speech-language therapists and other kinds of professionals can help your child work on this.

You can also play games at home that use rhyming and deleting sounds in words to help your child improve his phonological awareness.

It may also help for your son to see how your mouth moves when you’re saying different sounds. And last but not least, be sure to give him plenty of opportunity to say these sounds himself.

About the Author

Portrait of Guinevere Eden

Guinevere Eden

Guinevere Eden, Ph.D., is a professor in the department of pediatrics and director of the Center for the Study of Learning (CSL) at Georgetown University Medical Center.

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