What is Central Auditory Processing (CAP)?
In simplistic terms, Central Auditory Processing, or CAP, is the brain’s ability to analyse and recognise different sounds and give them meaning for us. Based on the physical characteristics of a sound (frequency, intensity and temporal features), the brain analyses the sound and then creates an ‘image’ of that sound. It then compares this image with other stored images in the brain; and when a match is found, we are able to recognise or understand that sound. In this way, we collect a bank of recognisable sounds that have important meaning in our lives (such as sirens, doorbells, crying, speech, etc.) If our brain picks up a sound for which it can’t find a match (e.g. a foreign language or a strange animal noise) it comes across as unrecognisable – thus we don’t understand it, nor can we prescribe any meaning to it.
Central Auditory Processing Disorder (CAPD)
Central Auditory Processing Disorder, or CAPD, is when the brain doesn’t analyse, process and store sound ‘images’ properly. Some children may have perfectly normal hearing but may show symptoms that are similar to hearing loss.
The result of CAPD is that these children may have difficulty understanding what they are hearing. They may also have trouble hearing speech which is degraded by background noise, or speech which is slightly unclear. They may have difficulty following instructions or cannot hear the subtle differences between words such as ‘sun’ and ‘fun’, or ‘cup’ and ‘cap’. This affects their phonemic awareness which in turn affects their later literacy, resulting in poor academic performance or performance below their cognitive abilities.
Children with CAPD have often had a history of middle-ear dysfunction at a critical time in their learning of speech sounds. CAPD can also evidence itself where there is a family history of similar difficulties, suggesting it could have a genetic component.
Children may begin to show signs of auditory difficulties from preschool age. Whilst auditory skills can be screened to assess potential weaknesses at a young age, at Northside Audiology we recommend allowing a child to mature before carrying out a formal assessment (from age seven onwards).
Two factors that influence CAP are memory and concentration
- Adequate auditory memory is essential for good auditory processing to take place. Both short term auditory memory and working memory help the child to match sounds with stored images of sounds, to arrange these sounds in a meaningful sequence, to attach meaning to these sounds and to manipulate these sounds with mental agility.
- Adequate concentration is also required to process sounds. Auditory and visual attention combine to determine our ability to concentrate on a task. It is important to establish whether a child has a general concentration problem or purely an auditory attention problem, before making a diagnosis of CAPD.
At Northside Audiology, we include both of these factors in our assessment of CAPD.