Dyslexia and the Auditory Deficit

Around 80% of children struggling with reading between the ages of 6 and 9 display an “auditory deficit”. There are several reasons for reading difficulty and dyslexia, but we have found this to be the most significant one by far.   A real solution to the auditory deficit can massively reduce the number of poor readers leaving primary school.

Currently around one in five children reach 11 unable to read proficiently.   So this is an issue for 600,000 children around the world in each academic year and about 30 million adults who are functionally illiterate with an auditory deficit.

The symptoms of an auditory deficit are a lot of guessing when reading (particularly with short words), an inability to decode a simple nonsense word like thrintock, mounbill or flognike and sometimes an ability to read text out loud without following the meaning.

So what is an auditory deficit and why is it a significant factor?

First I need to explain the two potential processes to reading text.   If you have the “little voice” in your head as you read this, you are using an auditory process.   On the other hand, if you are recognising words visually and guessing or skipping the ones you are not sure about, then you are using a visual process.

Let’s look at the auditory process first. The image of the text lands on your retinas (at the back of your eyes) and the signal is passed to your visual cortex.   The visual cortex, at the back of your head, analyses it and recognises the patterns of the letters.   

That information is then passed to your auditory cortex, in your left hemisphere close to your left ear, where the letter patterns are mapped to corresponding possible sounds.   In English there are 204 letter patterns that represent roughly 70 individual sounds.   So they are not one-to-one relationships, but there is a code, nonetheless.

The most likely sounds are then blended to form the word and that is passed to the linguistic cortex beside your left cheekbone.   The linguistic cortex has two distinct areas to it.   The posterior zone (nearest your ear) is for comprehension of language and is called Wernicke’s area.   The anterior zone (nearest your left eyebrow) is called Broca’s area and is used for the production of language.   

Therefore it is Wernicke’s area that turns the blended word from the auditory cortex into meaning and passes that to your prefrontal cortex at the front of your brain.   That is where you “think” about stuff in a conscious manner.

If you are reading out loud, you then connect to Broca’s area in order to generate speech, although it is possible to loop straight from Wernicke’s area to Broca’s area, which leads to that rather monotone reading style, absent of any intonation.

In contrast to all of that, the visual reader loops straight from the visual cortex to the prefrontal cortex.   The word cow, for instance, is processed in much the same way as a picture of a cow.   The auditory cortex remains dormant.   That is why it is called an auditory deficit.   The absence of activity in the auditory cortex can be seen on an MRI scan.

The reason that this visual approach is substantially less effective to read by than the auditory method is that the average brain is incapable of memorising more than a few hundred words.  Therefore reading anything more than simple text leads to a lot of holes in the flow of meaning.   

There is of course a range of ability in everything and some people with virtually photographic memories will be able to memorise more words than that.   And some highly experienced readers (like lawyers and academics) will combine both approaches by skimming a text visually at high speed and then zoning in on just the important parts using a slower auditory process.   But the effectiveness of the skimming is dependent on their ability to read any word as well.

Unfortunately, the children who are reading visually seem to do well initially and are unaware that they are heading in the wrong direction.   In year 1 and perhaps year 2 of school everyone is happy.   But somewhere between the ages of 6 and 9 they will move onto a reading plateau as the text gets more complicated and the task just seems to get harder and harder.   

You will often then see a lot of frustration and anxiety.  This normally translates into a strongly negative emotion towards reading and substantial resistance to further efforts. The whole thing can get very upsetting for both child and parents.

But here is the important thing to understanding this.   

The fact that they have not engaged their auditory cortex has conventionally been blamed on an unidentified “problem” with that part of their brain.

We have found that to be profoundly wrong, except in very rare cases.

The children are showing no problem with their auditory and linguistic cortex if they can hear and speak language successfully.   So why do we think it suddenly malfunctions when used for reading?

The truth is that the visual to prefrontal connection is a very strong one.   We are using it all the time.   It is a “natural” process in the sense that it has been developed over millions of years of evolution.   By contrast, the visual to auditory connection is only used for reading.   It is a connection we have created in the last 5000 years and is therefore not “natural”.   

Therefore it is not that the children can’t engage their auditory cortex in the reading process.   It is just that they haven’t.   They have naturally gone down the other path.

In order to fix the auditory deficit it is necessary to “re-engineer” the neurology of the reading process for the child, by rerouting it through the auditory cortex.  But that is absolutely possible and often gets very quick results.   With the right guidance we often find the penny drops in a matter of weeks.  

Of course the longer a child has been developing a visual approach to text, the harder it is to switch.   But that certainly does not make it impossible.   The ages 6-9 are the ideal for fixing the situation, but we have worked successfully with 70-year-olds too!   It is never too late.

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