Auditory processing disorder
Encyclopedia
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. It is not a peripheral hearing disorder (inner ear
) as individuals with APD usually have normal peripheral hearing ability. 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 (e.g., brain).
APD can affect both children and adults, although the actual prevalence is currently unknown. Males are two times more likely to be affected by the disorder than females.
) 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. The UK
's Medical Research Council
has also defined the disorder in a pamphlet, Auditory Processing Disorder (APD) pamphlet, Oct 2004.
Auditory processing disorder can be genetic or acquired. It may result from ear infections, head injuries or developmental delays that cause central nervous system
difficulties 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."
, 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.
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 until after the fact.
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. Modality specificity has been advocated as a way to improve APD diagnosis. There are several limitations to the approach suggested by proponents of modality specificity testing, including: major differences between primary auditory and visual cortices in the way information is coded and processed, how such approaches would separate children with both visual and auditory processing deficits from children with supramodal deficits, cross modal test equivalence, clinical infeasibility of visual processing test administration, lack of appropriate visual analogs to be used by audiologists, redundancy of modality specificity testing with neuropsychological assessment, and non-modularity of the central nervous system, among others.
The July 2001 volume of 'The Hearing Journal' has the article "Auditory Processing Disorder: An Overview for the Clinician". This summarizes the numerous disorders one can have from neuro/brain damage (notably amygdala). From severe TBIs to prolonged stress/trauma, - the amygdala can endure damage affecting so many cognitive functions, namely auditory functions.
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. Those suffering from APD may have 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. Background noise, such as the sound of a radio, television or a noisy bar can make it difficult to impossible to understand speech, depending on the severity of the auditory processing disorder. Using a telephone can be problematic for someone with auditory processing disorder, in comparison with someone with normal auditory processing, due to low quality audio, poor signal, intermittent sounds and the chopping of words. 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.
, dyslexia, learning difficulties, hearing loss, and psychologically-based behavioral problems.
APD may be related to cluttering
, a fluency disorder marked by word and phrase repetitions.
There is no research supporting the following APD treatments:
.
SLI 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 SLI. Unlike those with SLI, those with APD can usually get the meaning of language from written words where those with SLI show problems with both heard and read words, demonstrating that the basic issue is not an auditory one.
Those with APD have auditory difficulty distinguishing sounds including speech from extraneous sounds, e.g. fans or other chatter. APD is purely about processing what you hear both verbal and non-verbal. For those who have SLI, difficulty processing verbal language is only one of many symptoms.
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
information. It is not a peripheral hearing disorder (inner ear
Inner ear
The inner ear is the innermost part of the vertebrate ear. In mammals, it consists of the bony labyrinth, a hollow cavity in the temporal bone of the skull with a system of passages comprising two main functional parts:...
) as individuals with APD usually have normal peripheral hearing ability. 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 (e.g., brain).
APD can affect both children and adults, although the actual prevalence is currently unknown. Males are two times more likely to be affected by the disorder than females.
Definitions
The American Speech-Language-Hearing Association (ASHAAmerican Speech-Language-Hearing Association
The American Speech–Language–Hearing Association is a professional association for speech–language pathologists, audiologists, and speech, language, and hearing scientists in the United States and internationally...
) 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. The UK
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
's Medical Research Council
Medical Research Council (UK)
The Medical Research Council is a publicly-funded agency responsible for co-ordinating and funding medical research in the United Kingdom. It is one of seven Research Councils in the UK and is answerable to, although politically independent from, the Department for Business, Innovation and Skills...
has also defined the disorder in a pamphlet, Auditory Processing Disorder (APD) pamphlet, Oct 2004.
Auditory processing disorder can be genetic or acquired. It may result from ear infections, head injuries or developmental delays that cause central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
difficulties that affect processing of auditory information. This can include problems with: "...sound localization
Sound localization
Sound localization refers to a listener's ability to identify the location or origin of a detected sound in direction and distance. It may also refer to the methods in acoustical engineering to simulate the placement of an auditory cue in a virtual 3D space .The sound localization mechanisms of the...
and lateralization (see also binaural fusion
Binaural fusion
Binaural fusion is a cognitive process that involves the "fusion" of different auditory information presented binaurally, or to each ear. In humans, this process is essential in understanding speech as one ear may pick up more information about the speech stimuli than the other...
); auditory discrimination; auditory pattern recognition; temporal aspects of audition, including temporal integration, temporal discrimination (e.g., temporal gap detection), temporal ordering, and temporal masking
Temporal masking
Temporal masking or "non-simultaneous masking" occurs when a sudden stimulus sound makes inaudible other sounds which are present immediately preceding or following the stimulus...
; auditory performance in competing acoustic signals (including dichotic listening
Dichotic listening
In cognitive psychology, dichotic listening is a procedure commonly used to investigate selective attention in the auditory system. In dichotic listening, two different auditory stimuli are presented to the participant simultaneously, one to each ear, normally using a set of headphones...
); 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."
Diagnosis
As APD is one of the more difficult information processing disorders to detect and diagnose, it may sometimes be misdiagnosed as ADD/ADHDAttention-deficit hyperactivity disorder
Attention deficit hyperactivity disorder is a developmental disorder. It is primarily characterized by "the co-existence of attentional problems and hyperactivity, with each behavior occurring infrequently alone" and symptoms starting before seven years of age.ADHD is the most commonly studied and...
, Asperger syndrome
Asperger syndrome
Asperger's syndrome that is characterized by significant difficulties in social interaction, alongside restricted and repetitive patterns of behavior and interests. It differs from other autism spectrum disorders by its relative preservation of linguistic and cognitive development...
and other forms of autism
Autism
Autism is a disorder of neural development characterized by impaired social interaction and communication, and by restricted and repetitive behavior. These signs all begin before a child is three years old. Autism affects information processing in the brain by altering how nerve cells and their...
, 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.
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 until after the fact.
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. Modality specificity has been advocated as a way to improve APD diagnosis. There are several limitations to the approach suggested by proponents of modality specificity testing, including: major differences between primary auditory and visual cortices in the way information is coded and processed, how such approaches would separate children with both visual and auditory processing deficits from children with supramodal deficits, cross modal test equivalence, clinical infeasibility of visual processing test administration, lack of appropriate visual analogs to be used by audiologists, redundancy of modality specificity testing with neuropsychological assessment, and non-modularity of the central nervous system, among others.
Causes
APD is not a unitary disorder, as any pathological involvement of the central auditory nervous system can cause auditory dysfunction. Some suspected or known causes include: delay in myelin maturation , chronic otitis media during critical periods of language development, ectopic cells in the auditory cortical areas, genetic predisposition, neurologic issues (e.g., stroke, seizures, head injury) , and auditory deprivation due to age related changes in hearing sensitivity.The July 2001 volume of 'The Hearing Journal' has the article "Auditory Processing Disorder: An Overview for the Clinician". This summarizes the numerous disorders one can have from neuro/brain damage (notably amygdala). From severe TBIs to prolonged stress/trauma, - the amygdala can endure damage affecting so many cognitive functions, namely auditory functions.
Characteristics
The National Institute on Deafness and Other Communication Disorders state that children with Auditory Processing Disorder often:- have trouble paying attention to and remembering information presented orally, and may cope better with visually acquired information
- have problems carrying out multi-step directions given orally; need to hear only one direction at a time
- have poor listening skills
- need more time to process information
- have low academic performance
- have behavior problems
- have language difficulties (e.g., they confuse syllable sequences and have problems developing vocabulary and understanding language)
- have difficulty with reading, comprehension, spelling, and vocabulary
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. Those suffering from APD may have 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. Background noise, such as the sound of a radio, television or a noisy bar can make it difficult to impossible to understand speech, depending on the severity of the auditory processing disorder. Using a telephone can be problematic for someone with auditory processing disorder, in comparison with someone with normal auditory processing, due to low quality audio, poor signal, intermittent sounds and the chopping of words. 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.
Secondary characteristics
APD shares some of these signs with related disorders, which may have other overlap areas, such as acquired brain injury, attention deficitsAttention-deficit hyperactivity disorder
Attention deficit hyperactivity disorder is a developmental disorder. It is primarily characterized by "the co-existence of attentional problems and hyperactivity, with each behavior occurring infrequently alone" and symptoms starting before seven years of age.ADHD is the most commonly studied and...
, dyslexia, learning difficulties, hearing loss, and psychologically-based behavioral problems.
APD may be related to cluttering
Cluttering
Cluttering is a speech disorder and a communication disorder characterized by speech that is difficult for listeners to understand due to rapid speaking rate, erratic rhythm, poor syntax or grammar, and words or groups of words unrelated to the sentence...
, a fluency disorder marked by word and phrase repetitions.
Remediations and training
Recent research has shown that practice with basic auditory processing tasks (i.e. auditory training) may improve performance on auditory processing measures and phonemic awareness measures (Moore et al., 2005). These auditory training benefits have also been recorded at the physiological level (Russo et al., 2005; Alonso & Schochat, 2009). Many of these tasks are incorporated into computer-based auditory training programs such as Earobics and Fast ForWord, an adaptive software available at home and in clinics worldwide.There is no research supporting the following APD treatments:
- Auditory Integration TrainingAuditory integration trainingAuditory integration training is a procedure pioneered in France by Guy Bérard, who promoted it as a cure for clinical depression and suicidal tendencies, along with what he said were very positive results for dyslexia and autism, although there has been very little empirical evidence regarding...
typically involves a child attending two 30-minute sessions per day for ten days. - Lindamood-Bell Learning Processes (particularly, the Visualizing and Verbalizing program)
- Physical activities that require frequent crossing of the midline (e.g., occupational therapyOccupational therapyOccupational therapy is a discipline that aims to promote health by enabling people to perform meaningful and purposeful activities. Occupational therapists work with individuals who suffer from a mentally, physically, developmentally, and/or emotionally disabling condition by utilizing treatments...
) - Sound Field Amplification
- Neuro-Sensory Educational Therapy
Relation to Specific language impairment
APD can also be confused with Specific language impairment (SLI)Specific language impairment
Specific language impairment is diagnosed when a child's language does not develop normally and the difficulties cannot be accounted for by generally slow development , physical abnormality of the speech apparatus, autistic disorder, acquired brain damage or hearing loss.-Overview:Specific...
.
SLI is more specifically a problem associated with the linking of words, both written and spoken, to semantics
Semantics
Semantics is the study of meaning. It focuses on the relation between signifiers, such as words, phrases, signs and symbols, and what they stand for, their denotata....
(meaning) and someone can have both APD and SLI. Unlike those with SLI, those with APD can usually get the meaning of language from written words where those with SLI show problems with both heard and read words, demonstrating that the basic issue is not an auditory one.
Those with APD have auditory difficulty distinguishing sounds including speech from extraneous sounds, e.g. fans or other chatter. APD is purely about processing what you hear both verbal and non-verbal. For those who have SLI, difficulty processing verbal language is only one of many symptoms.
See also
- Active listeningActive listeningActive listening is a communication technique that requires the listener to understand, interpret, and evaluate what they hear. The ability to listen actively can improve personal relationships through reducing conflicts, strengthening cooperation, and fostering understanding.When interacting,...
- Asperger syndromeAsperger syndromeAsperger's syndrome that is characterized by significant difficulties in social interaction, alongside restricted and repetitive patterns of behavior and interests. It differs from other autism spectrum disorders by its relative preservation of linguistic and cognitive development...
- Attention-Deficit Hyperactivity DisorderAttention-deficit hyperactivity disorderAttention deficit hyperactivity disorder is a developmental disorder. It is primarily characterized by "the co-existence of attentional problems and hyperactivity, with each behavior occurring infrequently alone" and symptoms starting before seven years of age.ADHD is the most commonly studied and...
- AudiologyAudiologyAudiology is the branch of science that studies hearing, balance, and related disorders. Its practitioners, who treat those with hearing loss and proactively prevent related damage are audiologists. Employing various testing strategies Audiology (from Latin , "to hear"; and from Greek , -logia) is...
- Auditory scene analysisAuditory scene analysisIn psychophysics, auditory scene analysis is the process by which the human auditory system organizes sound into perceptually meaningful elements. The term was coined by psychologist Albert Bregman...
- Cocktail party effectCocktail party effectThe cocktail party effect describes the ability to focus one's listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations. The effect enables most people to talk in a noisy place...
- Cognitive scienceCognitive scienceCognitive science is the interdisciplinary scientific study of mind and its processes. It examines what cognition is, what it does and how it works. It includes research on how information is processed , represented, and transformed in behaviour, nervous system or machine...
- Echoic memoryEchoic memoryEchoic memoryis a type of sensory memory and auditory in nature; a component of sensory memory that is specific to retaining auditory information. Unlike visual memory, in which our eyes can scan the stimuli over and over, the auditory stimuli cannot be scanned over and over. Auditory stimuli is...
- Language processingLanguage processingLanguage processing refers to the way human beings process speech or writing and understand it as language. Most recent theories back the idea that this process is made completely by and inside the brain.- Spoken language :...
- King-Kopetzky syndromeKing-Kopetzky syndromeKing–Kopetzky syndrome is an auditory disability which appears as clinically as a “normal” hearing threshold.It is also known as auditory processing disorder or auditory disability with normal hearing ,...
(now included in the UK Medical Research Councils definition of APD) - Pure word deafnessPure word deafnessPure Word Deafness is caused by bilateral damage to the posterior superior temporal lobes or disruption of connections between these areas. It exhibits itself as inability to comprehend the meaning of speech, but still being able to hear, speak, read, and write.-Presentation:The underlying...
- Spatial hearing lossSpatial hearing lossSpatial hearing loss, also known as spatial processing deficit, refers to a form of deafness that is an inability to use spatial cues, i.e. where a sound originates from in space, to understand speech in the presence of background noise...