Auditory processing

Auditory processing is the interpretation of the sounds which have been heard. Our brain is required to make meaning of the incoming sounds by identifying and analysing them. Put simply, auditory processing is what we do with the auditory information we receive.

This is not to be confused with hearing, which is the physical ability of the component parts of the ear to receive sound and to pass this information on to the brain. Hearing is a sense, fully present at birth, which is innate – providing the physical structures are intact.

Listening is the learnt behaviour we use to pay attention to the sounds we hear. Children have to learn to listen. Our listening skills depend on an adequate experience of sound and are closely linked to vision, memory and the ability to learn.

Central auditory processes are responsible for four important functions: auditory discrimination, figure-ground discrimination, auditory memory and auditory sequencing.

• Auditory discrimination is the ability to distinguish and notice the difference between distinct and separate sounds, such as the difference between ‘bet’ and ‘pet’. Most children will muddle sounds such as ‘f’ and ‘th’ as they develop their language skills, but they should learn to perceive the difference.

• Figure-ground discrimination is the ability to differentiate certain sounds and filter these out from background noise or to pick out one voice from the collective sound of many.

• Auditory memory is the ability to remember what we hear, both long- and short-term, without having to rely on the reinforcement of such memories by writing things down.

• Auditory sequencing is the ability to recall the order of sounds, such as digits in numbers, or the sounds within words, and is also the ability to hold a sequence of instructions in order to follow these out.

Additional aspects of auditory processing include

• auditory sensitivity, which is the perception of the loudness or perceived volume of sound. Those who are hypersensitive to sound over-react to ‘normal’ sound and may find ordinary sounds intrusive and difficult to ignore. Hyposensitivity results in a reduced response to sound.
• auditory attention, which is the ability to select a sound and hold the attention on that sound, without being distracted by other stimuli. A fully functioning working memory (the temporary holding of information for perceptual and linguistic processing) is an integral part of the skill of attention

In summary, the auditory processing function for all sounds heard requires the ability to

• recognise sounds, their rhythms and patterns
• discriminate between sounds which are similar
• localise sound and hold one’s attention to that sound
• select target sounds in background noise
• notice the order in which sounds are made
• cope with a degraded signal using memory and past experience

Development of the auditory processing centres requires stimulation and is at its greatest when a child is young: hence the exponential growth in vocabulary between 12 and 24 months of age. But the brain’s plasticity means that changes and improvements in auditory processing can be made at any age, although the earlier intervention is started the better.