Auditory processing disorder

Auditory processing disorder (APD) is a neurodevelopmental disorder affecting the way the brain processes sounds. Individuals with APD usually have normal structure and function of the ear, but 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.

A subtype is known as King–Kopetzky syndrome or auditory disability with normal hearing (ADN), characterised by difficulty in hearing speech in the presence of background noise. This is essentially a failure or impairment of the cocktail party effect (selective hearing) found in most people.

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. It can affect both children and adults, and may continue to affect children into adulthood. Although the actual prevalence is currently unknown, it has been estimated to impact 2–7% of children in US and UK populations. Males are twice as likely to be affected by the disorder as females.