CENRAL AUDITORY PROCESSING DEFICIT (CAPD)

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Central Auditory Processing Deficit (CAPD)

This has to be high on the list of consideration as it is perhaps the most commonly encountered deficit under the ‘Dyslexia’ umbrella. Perversely, it makes phonic skills both difficult and essential.

CAPD must be one of the least understood and most frustrating processing deficits. As is the case most of the time, the longer it remains undiagnosed and untreated the greater the learning gap according to age and the more difficult it becomes to remediate. When it is coupled with high intellectual capacity, student frustration levels are particularly severe. Untreated it can produce character changes born of stress & anxiety such as a drop in self-worth, anger, task avoidance, disruptive behaviour etc.

  • CAPD / The Underlying Causes
  • CAPD / What can I do?
Tab 1

Central Auditory Processing Deficit
The underlying cause of many cases of reading failure

So why doesn’t phonics work with these students? It’s all to do with timing. They can’t process auditory information at the same speed as other students. The information simply ‘passes by them’. The brain has no idea what to do when asked to ‘blend’ or ‘decode’ as it has no prior experience – it hasn’t had the opportunity to learn, the chance to set up an area for processing such information. It’s a bit like us trying to listen to a recording that is played at high speed. We have difficulty processing what is being said as the information is coming in too fast – but – if we concentrate we can improve, but only because our brains have already set up the ‘auditory processing centre' referred to by Stanislav Dehaene as the 'letter box'. We are not born with a 'letter box', only by the recently discovered plasticity of the brain are we able to evolve this brain function. See How the Brain Reads from the menu or follow this link for more information on this topic.

You will now appreciate that there is a two fold problem.
a) the speed of the auditory input and
b) the lack of a brain processing mechanism.
This deficit is often referred to as Phonological Coding Deficit and is the most common problem experienced by failing readers but one that is seldom discussed.

The most profound problem manifests as an inability to recognise rhyme. If I say to a student “Eenie, meenie, minee, mouse, have you been creeping round my ?? - and leave him to finish the rhyme he is likely to say something like ‘shed’ or perhaps ‘shoe’. If I then suggest ‘house’ he might ask why is it ‘house’ and not ‘shed’. When this occurs the tutor knows there is a bumpy road ahead.

Less critical is the student who can recognise rhyme but can’t hear the sounds within a given word. The word ‘sand’ is heard clearly enough but the student can’t identify what the first, middle or last sounds are.

Were I to ask a question like, “What would happen if I took off the ‘sss’ (sound) and put on a ‘h’?What word would I make?” I would receive a puzzled or apprehensive look, for the student wouldn’t have a clue what I was talking about.

Frequently we see such students fail again and again when introduced to phonics, with the tutor giving up and a label of ‘dyslexia’ attached to the hapless child. This is because teacher-training courses frequently fail to cover the knowledge base required for teachers to assist students to overcome this critical hurdle.

In tab 2 I’ll outline some effective strategies for overcoming this deficit.

Tab 2

Central Auditory Processing Deficit
What can I do?

Use the TASSI approach (trace and sound sensory integration) as described in this web site:
See the menu or follow this link.

- with the addition of the following technique:


Slow speak synthesis (SSS)

Knowing that the processing timing is delayed it makes sense to slow everything down so that the brain DOES have the time and the opportunity to process the sounds within the words.

The second consideration is that not all letter sounds can be drawn out. Most of those that can't are called 'explosives'. The sounds that can't be easily drawn out are: b, c, d, g, j, k, p, qu, t, and x. When teaching students with central auditory processing deficits the above sounds cannot be used at the beginning or in the body of the word. They can be used on the end. The word 'nip' (nnniiip) can be used but not the word 'pin' (piiinnn).

The third aspect is that it is necessary for the brain, for the first time, 'gets it' because it is, for the first time, slow enough to hear that the word is actually composed of a number of sounds. Once the brain develops the ability to process the sounds in sequence to arrive at a word two things happen:
a) The teacher can begin to speed up the process.
b) As the student begins to blend faster, the explosives can be introduced to the beginning of the words.

When my students aren't sure of a new word they will often say "Can you slow speak it or me?" We don't process our own voice exactly the same way as we process other people's voices, sometimes it seems to assist the students to have another 'slow-speak' a word for them.

When working on spelling, it is important that the student then mimics the tutor's 'slow speak' so that they respond to their own voice. The reason for this is that most of the time the student is relying most on his own spoken or internal voice when story writing, so this is the brain response that needs to be exercised most.

This process takes time and CANNOT be 'hurried along'. Once the student overcomes this major hurdle, progress gradually increases over time.

In my 14 years in the learning centre I encountered only two students with this particular deficit who did not respond to this technique. Those two students did learn to read but were quite severely limited in both reading and spelling.

There is a programme available specifically designed to correct central auditory processing deficits called 'FastForWord'. This computer programme is capable of slowing down the explosive sounds electronically and claims good results. It is, however, quite costly and involves the student spending time at a specialist clinic.

One of the best moments in teaching is observing that moment when a student with central auditory processing says, "Oh, I get it now." You know that with some dedicated work this student will be OK. He/she may take a little longer than the average student to read a passage but both the reading and the comprehension will be accurate. As fluency builds, seldom will they need to reread a passage to clarify the meaning.


As with all learning deficits, VAS levels can be a compounding factor.