What is Auditory Processing?
Auditory processing is what we do with sound information, that is: “What we do with what we hear”
Sound waves travel through the air and are collected by our outer ear (Pina). The sound then travels down the ear canal, causing the ear drum to vibrate, in turn causing the bones of the middle ear to vibrate. The sound is then received by the inner ear (the cochlear system and vestibular system). The sound stimulates nerve cells in the cochlear system, which coverts the sound information into electro chemical signals.
These signals pass along nerves and travel to the auditory cortex where the sound is consciously heard. This engages the cortex and all functions of the brain which processes the representative sound information – thus listening occurs.
Many brain systems and sub-systems are involved in the processing of this information – including those involved in attention, memory, and higher order cognitive functions.
Thus auditory processing does not describe hearing. Many people with Auditory Processing Difficulties have perfect hearing (as tested by an audiologist/ hearing test) but there is a deficit in the processing of the message that has been heard.
A person with APD may not be able to process what is said to them. They appear to have heard what has been said as they can sometimes even repeat back exactly what has been said, but they have not attached any meaning to the sentence, they have not processed it. They know the words, but the words are meaningless.
If a person is not processing the message, repeating the message will be of no use, neither will speaking louder! Auditory Processing difficulties can fluctuate from day to day. This can be very frustrating for parents, teachers and the person themselves as on one day they appear to be processing well (as indicated by their behaviour) while on other days they may not be able to process anything at all.
Diagnosis – Formalisation of symptoms
Many people with APD have difficulty following directions (especially multi part directions), difficulty expressing themselves, difficulty with comprehension (including reading comprehension). Difficulty in social situations (as it is often very hard for these children to keep up with a conversation or understand what other children are saying).
Other people who may have a more profound developmental delay and an auditory processing difficulty may engage in auditory self stimulation such as humming of talking to themselves. In addition, some people are highly sensitive to certain sounds (generally low frequency sounds) sometimes to such an extent that they cause physical pain.
Children who have had many ear infections or have had fluid in the middle ear are at a higher risk for auditory processing difficulties.
The written word is an extension of language information – it is the visual representation of auditory communication. Thus auditory processing difficulties can extend to reading and writing (as a result Auditory processing can be one of the major causes of Dyslexia).