Auditory processing disorder

# Overview
Auditory Processing Disorder (APD) (previously known as "Central Auditory Processing Disorder" (CAPD) is a disorder in how auditory information is processed in the brain. It is not a sensory (inner ear) hearing impairment; individuals with APD usually have normal peripheral hearing ability. APD is an umbrella term that describes a variety of problems with the brain that can interfere with processing auditory information.

# Definitions
The American Speech-Language-Hearing Association (ASHA) published their first definitive Technical Report "(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)", and complements the UK's "Medical Research Council's Institute of Hearing Research's" Auditory Processing Disorder (APD) pamphlet, Oct 2004.
Auditory processing disorder can be a congenital or an acquired condition (for example; resulting from ear infections and head injuries) which refers to difficulties in the processing of auditory information within the central nervous system, such as problems with: "...sound localization and lateralization; 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." (Quote from: (Central) Auditory Processing Disorders, Technical Report, Jan 2005)

# Pathophysiology
Although the cause is Neurological (emanating from the Central Nervous System), rather than Audiological (associated with ear abnormalities), APD can sometimes be complicated by cochlear (inner ear) dysfunction which may be a separate, co-morbid condition. Therefore, a patient with this disorder might be better understood by a Neurologist, even though a consultation with an Ear Specialist might also be useful to rule out ear disorders. An assessment by a Neuropsychologist could be useful (in making the differential diagnosis) and excluding  possible co-morbid Psychiatric or Psychological causes.
APD can manifest as problems determining the direction of sounds, difficulty perceiving differences between speech sounds and the sequencing of these sounds into meaningful words, confusing similar sounds such as "hat" with "bat", "there" with "where", etc. Fewer words may be perceived than were actually said, as there can be problems detecting the gaps between words, creating the sense that someone is speaking unfamiliar or nonsense words. Problems relating what has been said with its meaning, despite obvious recognition that a word has been said, as well as repetition of the word. Separating speech sounds from background noise, pink sound, such as the sound of a radio, television or a noisy bar, it can be difficult to impossible to understand speech, depending on the severity of the auditory processing disorder. Using a telephone can be problematic, due to low quality audio, poor signal, intermittent sounds and the chopping of words can be a problem for someone with Auditory processing disorder to cope with, in comparison with someone with normal auditory processing (hearing).
Many who have auditory processing disorder subconsciously develop visual coping strategies, such as lip reading, reading body language, and eye contact, to compensate for their auditory deficit, and these coping strategies are not available when using a telephone.

# Causes
There are many possible causes of APD. They can include head trauma, lead poisoning, and chronic ear infections. It can also be inherited or genetic. Because there are many different possibilities, each person must be assessed individually.

# Diagnosis
APD is recognized as a major cause of dyslexia. As APD is one of the more difficult information processing disorders to detect and diagnose, it may sometimes be misdiagnosed as ADD/ADHD, Aspergers and other more severe 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 who were not aware of APD would diagnose the disabilities as those which they were aware of.  APD can also be confused with Language Processing Disorder.  Unlike APD, LPD is more specifically a problem associated with the linking of words, both written and spoken, to semantics (meaning) and someone can have both APD and LPD.  Unlike those with LPD, those with APD can usually get the meaning of language from written words where those with LPD show problems with both heard and read words, demonstrating that the basic issue is not an auditory one.
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 an Auditory (Verbal) Processing Disorder, and text is only verbal code, and so the Auditory Processing Disorder is extended into reading and writing as this auditory code. As a consequence, APD has been recognized as one of the major causes of dyslexia.
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.

# History
Some of the characteristics of APD may be observed in individuals with other types of deficits or disorders, such as acquired brain injury, attention deficits, dyslexia or learning difficulties, hearing loss, and psychologically-based behavioral problems.  APD may be related to cluttering, a fluency disorder marked by word and phrase repetitions.

# Symptoms
Persons with this condition often:
- have trouble paying attention to and remembering information presented orally; cope better with visually acquired information
- have problems carrying out multi-step directions given orally; need to hear only one direction at a time
- appear to have poor listening skills, and need people to speak slowly
- need more time to process information.
It appears to others as a problem with listening. Somebody with APD may be accused of "not listening".

# Coping Skills and Management
Adults who discover disabilities such as APD late in life have provided some insight into coping skills they have found helpful. These include:
- Ask people to speak slowly, especially on the telephone.
- If someone is giving you several pieces of information together, repeat each one aloud as you hear it. This allows the brain the necessary time to assimilate the last message before receiving a new one.
- Get directions and instructions in writing.
- When given a unit of information e.g. a number, immediately form a mental picture of it. Visual messages are much easier for APD sufferers to store in memory.
- Do not take notes yourself when information comes from others orally, as this may interfere with your processing strategies, but ask others to provide notes for you.
- Many APDs use body language, lip reading and eye contact as a coping strategy.
- Rewrite text using multi-coloured text options to provide visual guide to changes in meaning or for new sentences, or use a set of coloured highlighters.
- Use closed captioning while watching television.
- Place with teachers whose speaking style is clear and organized, who are "good explainers," and who encourage questions, so that the person with APD does not have to decode complex verbiage. Rules of language activities, including writing, need to be made overt and very explicit.

# Remediations and Training
No one program is a cure or help all for APD. There are no research supported treatments for APD available, however a variety of treatments have been offered commercially in the absence of solid empirical research support for their efficacy.
APD is about creating coping strategies to meet the challenges life presents and using the various strengths each of us may have.
- Management of Auditory Processing Disorders (includes the use of many programs)
- AIT Institute for Auditory Integration Training. Free resources, information and referrals to AIT Practitioners worldwide.
- Lindamood-Bell Learning Processes (particularly, the Visualizing and Verbalizing program)
- Physical activities which require frequent crossing of the midline (e.g. occupational therapy)
- Sound Field Amplification

## APD and Dyslexia
Auditory Processing Disorder may also be an underlying cause of dyslexia. "auditory performance in competing acoustic signals" (including dichotic listening)).