Auditory processing disorder | |
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Classification and external resources | |
ICD-9-CM | 388.45 388.40 |
MeSH | D001308 |
Auditory processing disorder (APD), also known as central auditory processing disorder (CAPD), is an umbrella term for a variety of disorders that affect the way the brain processes auditory information. Individuals with APD usually have normal structure and function of the outer, middle and inner ear (peripheral hearing). However, they cannot process the information they hear in the same way as others do, which leads to difficulties in recognizing and interpreting sounds, especially the sounds composing speech. It is thought that these difficulties arise from dysfunction in the central nervous system.
The American Academy of Audiology notes that APD is diagnosed by difficulties in one or more auditory processes known to reflect the function of the central auditory nervous system.
APD can affect both children and adults, although the actual prevalence is currently unknown. It has been suggested that males are twice as likely to be affected by the disorder as females, but there are no good epidemiological studies.
The American Speech-Language-Hearing Association (ASHA) published "(Central) Auditory Processing Disorders" in January 2005 as an update to the "Central Auditory Processing: Current Status of Research and Implications for Clinical Practice (ASHA, 1996)". The American Academy of Audiology has released more current practice guidelines related to the disorder
In 2011, the British Society of Audiology published 'best practice guidelines'.
Auditory processing disorder can be developmental or acquired. It may result from ear infections, head injuries or neurodevelopmental delays that affect processing of auditory information. This can include problems with: "...sound localization and lateralization (see also binaural fusion); auditory discrimination; auditory pattern recognition; temporal aspects of audition, including temporal integration, temporal discrimination (e.g., temporal gap detection), temporal ordering, and temporal masking; auditory performance in competing acoustic signals (including dichotic listening); and auditory performance with degraded acoustic signals."
The Committee of UK Medical Professionals Steering the UK Auditory Processing Disorder Research Program have developed the following working definition of Auditory Processing Disorder: "APD results from impaired neural function and is characterized by poor recognition, discrimination, separation, grouping, localization, or ordering of speech sounds. It does not solely result from a deficit in general attention, language or other cognitive processes."