auditory processing disorder auditory processing disorder auditory processing disorder (apd), rarely known as king-kopetzky syndrome or auditory disability with normal hearing (adn), is a neurodevelopmental disorder affecting the way the brain processes sounds. 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. auditory processing disorderother namescentral auditory processing disorderspecialtyaudiology, neurology 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. although the actual prevalence is currently unknown, it has been estimated to be 2–7% in children in us and uk populations. apd can continue into adulthood. cooper and gates (1991) estimated the prevalence of adult apd to be 10 to 20%. it has been reported that males are twice as likely to be affected by the disorder as females, and that prevalence is higher in the elderly and increases with age. neurodevelopmental forms of apd are differentiable from aphasia in that aphasia is by definition caused by acquired brain injury, but acquired epileptic aphasia has been viewed as a form of apd. signs and symptoms many people experience problems with learning and day-to-day tasks with difficulties over time. adults with this disorder can experience the signs and symptoms below: talk louder than necessary talk softer than necessary have trouble remembering a list or sequence often need words or sentences repeated have poor ability to memorize information learned by listening interpret words too literally need assistance hearing clearly in noisy environments rely on accommodation and modification strategies find or request a quiet work space away from others request written material when attending oral presentations ask for directions to be given one step at a time relation to attention deficit hyperactivity disorder it has been discovered that apd and adhd present overlapping symptoms. below is a ranked order of behavioral symptoms that are most frequently observed in each disorder. professionals evaluated the overlap of symptoms between the two disorders. the order below is of symptoms that are almost always observed. this chart shows that although the symptoms listed are different, it is easy to get confused between many of them. adhdapd 1. inattentive1. difficult hearing in background noise 2. distracted2. difficulty following oral instructions 3. hyperactive3. poor listening skills 4. fidgety or restless4. academic difficulties 5. hasty or impulsive5. poor auditory association skills 6. interrupts or intrudes6. distracted 7. inattentive there is a co-occurrence between adhd and apd. a systematic review published in 2018 detailed one study that showed 10% of children with apd have confirmed or suspected adhd. it also stated that it is sometimes difficult to distinguish the two, since characteristics and symptoms between apd and adhd tend to overlap. the systematic review mentioned here described this overlap between apd and other behavioral disorders and whether or not it was easy to distinguish those children that solely had auditory processing disorder. relation to specific language impairment and developmental dyslexia there has been considerable debate over the relationship between apd and specific language impairment (sli). sli is diagnosed when a child has difficulties with understanding or producing spoken language for no obvious cause. the problems cannot be explained in terms of peripheral hearing loss. the child is typically late in starting to talk, and may have problems in producing speech sounds clearly, and in producing or understanding complex sentences. some theoretical accounts of sli regard it as the result of auditory processing problems. however, this view of sli is not universally accepted, and others regard the main difficulties in sli as stemming from problems with higher-level aspects of language processing. where a child has both auditory and language problems, it can be difficult to sort out the causality at play. similarly with developmental dyslexia, researchers continue to explore the hypothesis that reading problems emerge as a downstream consequence of difficulties in rapid auditory processing. again, cause and effect can be hard to unravel. this is one reason why some experts have recommended using non-verbal auditory tests to diagnose apd. specifically regarding neurological factors, dyslexia has been linked to polymicrogyria which causes cell migrational problems. children that have polymicrogyri almost always present with deficits on apd testing. it has also been suggested that apd may be related to cluttering, a fluency disorder marked by word and phrase repetitions. it has been found that a higher than expected proportion of individuals diagnosed with sli and dyslexia on the basis of language and reading tests also perform poorly on tests in which auditory processing skills are tested. apd can be assessed using tests that involve identifying, repeating or discriminating speech, and a child may do poorly because of primary language problems. in a study comparing children with a diagnosis of dyslexia and those with a diagnosis of apd, they found the two groups could not be distinguished. analogous results were observed in studies comparing children diagnosed with sli or apd, the two groups presenting with similar diagnostic criteria. as such, the diagnosis a child receives may depend on which specialist they consult: the same child who might be diagnosed with apd by an audiologist may instead be diagnosed with sli by a speech-language therapist or with dyslexia by a psychologist. causes acquired acquired apd can be caused by any damage to or dysfunction of the central auditory nervous system and can cause auditory processing problems. for an overview of neurological aspects of apd, see t. d. griffiths's 2002 article "central auditory pathologies". genetics some studies have indicated an increased prevalence of a family history of hearing impairment in these patients. the pattern of results is suggestive that auditory processing disorder may be related to conditions of autosomal dominant inheritance. the ability to listen to and comprehend multiple messages at the same time is a trait that is heavily influenced by our genes, say federal researchers. these "short circuits in the wiring" sometimes run in families or result from a difficult birth, just like any learning disability. auditory processing disorder can be associated with conditions affected by genetic traits, such as various developmental disorders. inheritance of auditory processing disorder refers to whether the condition is inherited from your parents or "runs" in families. central auditory processing disorder may be hereditary neurological traits from the mother or the father. developmental in the majority of cases of developmental apd, the cause is unknown. an exception is acquired epileptic aphasia or landau-kleffner syndrome, where a child's development regresses, with language comprehension severely affected. the child is often thought to be deaf, but normal peripheral hearing is found. in other cases, suspected or known causes of apd in children include delay in myelin maturation, ectopic (misplaced) cells in the auditory cortical areas, or genetic predisposition. in a family with autosomal dominant epilepsy, seizures which affected the left temporal lobe seemed to cause problems with auditory processing. in another extended family with a high rate of apd, genetic analysis showed a haplotype in chromosome 12 that fully co-segregated with language impairment. hearing begins in utero, but the central auditory system continues to develop for at least the first decade. there is considerable interest in the idea that disruption to hearing during a sensitive period may have long-term consequences for auditory development. one study showed thalamocortical connectivity in vitro was associated with a time sensitive developmental window and required a specific cell adhesion molecule (lcam5) for proper brain plasticity to occur. this points to connectivity between the thalamus and cortex shortly after being able to hear (in vitro) as at least one critical period for auditory processing. another study showed that rats reared in a single tone environment during critical periods of development had permanently impaired auditory processing. "bad" auditory experiences, such as temporary deafness by cochlear removal in rats leads to neuron shrinkage. in a study looking at attention in apd patients, children with one ear blocked developed a strong right-ear advantage but were not able to modulate that advantage during directed-attention tasks. in the 1980s and 1990s, there was considerable interest in the role of chronic otitis media (middle ear disease or "glue ear") in causing apd and related language and literacy problems. otitis media with effusion is a very common childhood disease that causes a fluctuating conductive hearing loss, and there was concern this may disrupt auditory development if it occurred during a sensitive period. consistent with this, in a sample of young children with chronic ear infections recruited from a hospital otolaryngology department, increased rates of auditory difficulties were found later in childhood. however, this kind of study will have sampling bias because children with otitis media will be more likely to be referred to hospital departments if they are experiencing developmental difficulties. compared with hospital studies, epidemiological studies, which assesses a whole population for otitis media and then evaluate outcomes, have found much weaker evidence for long-term impacts of otitis media on language outcomes. somatic it seems that somatic anxiety (that is, physical symptoms of anxiety such as butterflies in the stomach or cotton mouth) and situations of stress may be determinants of speech-hearing disability. diagnosis questionnaires can be used for the identification of persons with possible auditory processing disorders, as these address common problems of listening. they can help in the decision for pursuing clinical evaluation. one of the most common listening problems is speech recognition in the presence of background noise. according to the respondents who participated in a study by neijenhuis, de wit, and luinge (2017), the following symptoms are characteristic in children with listening difficulties, and they are typically problematic with adolescents and adults. they include: difficulty hearing in noise auditory attention problems better understanding in one on one situations difficulties in noise localization difficulties in remembering oral information according to the new zealand guidelines on auditory processing disorders (2017) a checklist of key symptoms of apd or comorbidities that can be used to identify individuals who should be referred for audiological and apd assessment includes, among others: difficulty following spoken directions unless they are brief and simple difficulty attending to and remembering spoken information slowness in processing spoken information difficulty understanding in the presence of other sounds overwhelmed by complex or "busy" auditory environments e.g. classrooms, shopping malls poor listening skills insensitivity to tone of voice or other nuances of speech acquired brain injury history of frequent or persistent middle ear disease (otitis media, "glue ear"). difficulty with language, reading, or spelling suspicion or diagnosis of dyslexia suspicion or diagnosis of language disorder or delay finally, the new zealand guidelines state that behavioral checklists and questionnaires should only be used to provide guidance for referrals, for information gathering (for example, prior to assessment or as outcome measures for interventions), and as measures to describe the functional impact of auditory processing disorder. they are not designed for the purpose of diagnosing auditory processing disorders. the new zealand guidelines indicate that a number of questionnaires have been developed to identify children who might benefit from evaluation of their problems in listening. examples of available questionnaires include the fisher's auditory problems checklist, the children's auditory performance scale, the screening instrument for targeting educational risk, and the auditory processing domains questionnaire among others. all of the previous questionnaires were designed for children and none are useful for adolescents and adults. the university of cincinnati auditory processing inventory (ucapi) was designed for use with adolescents and adults seeking testing for evaluation of problems with listening and/or to be used following diagnosis of an auditory processing disorder to determine the subject's status. following a model described by zoppo et al. (2015) a 34-item questionnaire was developed that investigates auditory processing abilities in each of the six common areas of complaint in apd (listening and concentration, understanding speech, following spoken instructions, attention, and other.) the final questionnaire was standardized on normally-achieving young adults ranging from 18 to 27 years of age. validation data was acquired from subjects with language-learning or auditory processing disorders who were either self-reported or