Diagnosis for Auditory Processing Disorder

As APD is one of the more difficult information processing disorders to detect and diagnose, it may sometimes be misdiagnosed as ADD/ADHD, Asperger syndrome and other forms of autism, but it may also be a comorbid aspect of those conditions if it is considered a significant part of the overall diagnostic picture. APD shares common symptoms in areas of overlap, such that professionals unfamiliar with APD might misdiagnose it as a condition they are aware of.

People with APD intermittently experience an inability to process verbal information. When people with APD have a processing failure, they do not process what is being said to them. They may be able to repeat the words back word for word, but the meaning of the message is lost. Simply repeating the instruction is of no use if a person with APD is not processing. Neither will increasing the volume help.

People with APD have a disorder processing auditory information within the brain. The written word is a visual notation of verbal language, thus Auditory Processing Disorder can extend into reading and writing.

There are also many other hidden implications, which are not always apparent even to the person with the disability. For example, because people with APD are used to guessing to fill in the processing gaps, they may not even be aware that they have misunderstood something.

APD has been defined anatomically in terms of the integrity of the auditory nervous system, as "what we do with what we hear", and in terms of performances on a selected group of behavioral auditory tests (Task Force for the American Speech, Language, and Hearing Association; ASHA, 1994). The ASHA Task Force definition considered APD to be any observed deficits in one or more of these so-called "behaviors". Problems inherent in test validation by consensus are highlighted by the succession of task force reports that have appeared in recent years. The first of these occurred in 1996. This was followed by a conference organized by the American Academy of Audiology that explicitly embraced modality specificity as a defining characteristic of auditory processing disorders. Subsequently, an ASHA committee rejected modality specificity as a defining characteristic of auditory processing disorders.

There have been several commentaries questioning various aspects of these proposals. Additionally, Moore suggests that APD is primarily a difficulty in processing non-speech sounds and that a population-based approach should be taken to identify outlying performers. However, inclusive conceptualizations of APD have been criticized based on their lack of diagnostic specificity. Auditory processing disorder has been defined as a modality specific perceptual dysfunction that is not due to peripheral hearing loss. This viewpoint emphasizes the perceptual nature of auditory processing and asserts that the disorder should be conceptualized as being limited to problems in processing auditory material. Numerous authors have suggested that existing tests of APD may be sensitive to factors that are not of an auditory perceptual nature. Modality specificity has been advocated as a way to improve APD diagnosis.