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Hearing Journal:
doi: 10.1097/01.HJ.0000294109.14504.d8
Page Ten

Auditory processing disorder: An overview for the clinician

Chermak, Gail D.

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PAGE TEN

It was not that long ago that the “central auditory test battery” for the average audiologist consisted of presenting a few PB words with some ipsilateral white noise masking tossed in. Depending on whose article you read, the performance for normals on this test could be anywhere from 35% to 75%, so whatever score the patient obtained was usually okay. Fortunately, a lot has changed since then, and we have many people to thank.

One of the first chapters on central auditory testing in an audiology text was by Ettore Bocca, the 1963 edition of Modern Developments in Audiology. It's still a good read today. I'm guessing that many of you cut your teeth in this area by attending a workshop given by Chuck Berlin or Jack Katz. If your primary interest was testing children, you probably were influenced by Jack Willeford or Bob Keith. Over the years, Frank Musiek and Jay Hall have continued to provide us with the “medical center” perspective of this specialty. And, of course, from the beginning, nearly everyone involved in this specialty has been influenced by the contributions of James Jerger.

Since Ettore's chapter, we've learned a lot—not only concerning the diagnosis of auditory processing disorders, but also regarding treatment and intervention strategies. To update us on the current status, we've invited another person who has contributed significantly to this area over the past several years, Gail D. Chermak, PhD.

Dr. Chermak is the Edward R. Meyer Distinguished Professor of Audiology and the chair of the Department of Speech and Hearing Sciences at Washington State University. She has chaired or served on several task forces and committees related to research and clinical practices in central auditory processing. Many of you are familiar with the popular book she co-authored with Frank Musiek—Central Auditory Processing Disorders: New Perspectives. Gail's contributions in this area have extended beyond the U.S. borders, as in the late 1980s she established a community-based resource and referral system in Trinidad for children and families needing evaluation and intervention. She continues to return to Trinidad to conduct workshops for professionals and parents.

Dr. Chermak has packed a wealth of information about auditory processing disorders into this Page Ten article. As an added bonus, she has provided an extensive reference list for those of you who want to continue your reading in this area. As you begin to read this excellent review, you'll quickly see that we've come a long way from the PBs-in-white-noise testing of the 1960s!

Gus Mueller

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1 To start with, what exactly is a central auditory processing disorder?

Before I define it, please allow me to update your terminology—no disrespect intended. In April 2000, 14 senior scientists and clinicians met at the Callier Center for Communication Disorders at the University of Texas at Dallas to reach consensus on issues related to diagnosing central auditory processing disorders in school-aged children. The Bruton Conference, as it has since become known, led not only to recommendations regarding diagnosis of this disorder, but also to some new terminology. The group agreed that a new label, auditory processing disorder, should replace the older label, central auditory processing disorder. The objective was to maintain an operational definition that emphasizes the interactions of disorders at both peripheral and central sites and does not impute anatomic loci.1 Hence, we are now referring to this clinical entity as auditory processing disorder or APD.

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2 All right, then, what is an auditory processing disorder?

The definition that emerged from the Bruton Conference cast APD as a deficit in the processing of information that is specific to the auditory modality, that may be exacerbated in unfavorable acoustic environments, and that may be associated with difficulties in listening, speech understanding, language development, and learning.1 APD is a complex and heterogeneous group of disorders usually associated with a range of listening and learning deficits.2,3

Underlying APD is a deficit observed in one or more of the auditory processes responsible for generating the auditory evoked potentials and the following behaviors: sound localization and lateralization; auditory discrimination; auditory pattern recognition; temporal aspects of audition, including temporal resolution, temporal masking, temporal integration, and temporal ordering; auditory performance with competing acoustic signals; and auditory performance with degraded acoustic signals.4

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3 If APD is auditory specific, why the range of associated learning deficits?

Well, first of all, APD is not a label for a unitary disease entity, but rather a description of functional deficits.2 Further, notwithstanding the primacy of auditory processing deficits in APD, the clinical linkages you refer to occur because all auditory tasks, from pure-tone perception to spoken language processing, are influenced by higher-level, non-modality-specific factors such as attention, learning, motivation, and decision processes.5-9

Auditory processes involve the deployment of non-dedicated, global mechanisms of attention and memory in service of acoustic signal processing.10-13 (There is a complex arrangement of shared physiologic and neurologic networks across these processes and mechanisms.14-17) Brain imaging studies and post-mortem examinations of individuals with a number of disorders associated with APD have revealed morphologic and structural differences in auditory areas of the brain (e.g., superior temporal gyrus, Heschl's gyrus, planum temporale, posterior portion of the insula, sulcus of the corpus callosum) that are activated when listening to simple tonal complexes, language, and music, and also in areas of the brain responsible for executive control, motor regulation, and behavioral inhibition (e.g., prefrontal cortex, striatum, amygdala).14,18–27

Not surprisingly, then, APD has been observed in a variety of clinical populations, including those associated with known lesions or pathology of the central nervous system (e.g., aphasia, Alzheimer's disease, traumatic brain injury) and others with suspected but unconfirmed central nervous system pathology or neurodevelopmental disorder (e.g., developmental language disorder, dyslexia, learning disabilities [LD], and attention deficit hyperactivity disorder [ADHD]). APD has also been reported in association with a history of chronic otitis media28-33 and has been documented in older adults due to neurologic changes resulting from the aging process.34-36 Multidisciplinary assessment and comprehensive intervention are necessary for APD given the overlapping symptomatology across these diverse clinical populations and the range of listening and learning deficits associated with APD.

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4 What behaviors might lead one to suspect APD?

Characteristically, individuals with APD have difficulty comprehending spoken language in competing speech or noise backgrounds and in reverberation. Children with APD frequently ask for repetitions, say “what” and “huh” a lot, have trouble paying attention, are easily distracted, often misunderstand messages, have trouble following complex auditory directions or commands, and find it difficult to localize sound.4,37 They also often present related deficits in auditory memory, phonologic awareness, reading, and academic achievement.1,4

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5 What is the prevalence of APD in children and adults?

Prevalence data for APD are sparse, particularly for children. We have estimated that APD occurs in 2% to 3% of children, with a 2:1 ratio between boys and girls.4 Cooper and Gates estimated APD in 10% to 20% of older adults.38 In contrast, Stach et al. reported APD in 70% of clinical patients over age 60 years.36 Differences in subject samples, test measures, and criteria for determining APD may account for the large difference in prevalence estimates.

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6 Does anybody know what causes APD?

Well, this is somewhat speculative, and there is no definitive answer at this time. However, three main categories of causation have been suggested, under which a number of specific etiologic agents could be operating.

A neuromorphologic disorder may account for 65% to 70% of children diagnosed with APD.4 Underlying APD in this group would be areas of polymicrogyri (i.e., underdeveloped and misshapen cells) and heterotopias (i.e., misplaced cells), most likely in the left hemisphere and the auditory region of the corpus callosum.39 Approximately 25% to 30% of pediatric APD might be the result of delay in the maturation of the central auditory nervous system.39,40 Neurologic disorders, diseases, and insults, including neurodegenerative disease, might account for under 5% of diagnosed APD in children, especially as APD relates to learning disability.39,41 This latter category would characterize the majority of acquired APD in adults.

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7 I've read that there is a relationship between APD and recurrent otitis media. Is this true?

There has been considerable, and continuing, research examining the possible relationships among otitis media and the gamut of auditory, linguistic, behavioral, and academic deficits (see Gravel and Wallace42 for a review). While some reports have concluded that there is no connection between recurrent otitis media (ROM) and APD,43-45 I am persuaded by the number of studies that have revealed evidence of a link between them.29,31,46,47

Specifically, findings of prolonged ABR waves and interwave intervals, reduced masking level differences, larger frequency-difference limens, and reduced speech recognition in noise and competition have been reported, with some evidence that the deficits may be long-term, persisting even years after hearing sensitivity returns to normal.28,29,31–33,48,49 It appears that it is the fluctuating hearing loss and associated auditory deprivation, not the ROM per se, that lead to these perceptual deficits.50,51

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8 Who diagnoses APD and on what basis?

Because of the heterogeneous nature of APD and the range of listening and learning deficits that often coexist with APD, comprehensive evaluation requires a multidisciplinary team approach.

APD is diagnosed by the audiologist on the basis of an extensive audiologic evaluation. Additional evaluation of receptive and expressive language, metalanguage, metacognition (e.g., executive function), and psychoeducational achievement is necessary, however, to identify associated (co-morbid) conditions, as well as to clarify the functional impact of APD. In fact, comprehensive assessment is necessary for the accurate differential diagnosis of APD from other “look-alike” disorders, most notably ADHD and language processing disorders.

Speech-language pathologists, psychologists, and educators contribute to this more comprehensive assessment. But, since I am an audiologist, as are many of the Journal's readers, I will outline the minimum audiologic test battery used to diagnose APD.

Behavioral tests are most commonly used to assess the auditory processing. Electrophysiologic (e.g., auditory brainstem response [ABR] and auditory middle latency response) and electroacoustic (e.g., immittance measures and otoacoustic emissions) procedures are more objective (i.e., less influenced by extraneous factors). Electrophysiologic measures are more time consuming and expensive and are not as widely used at this time. Neuroimaging, a third approach to assessment, offers great promise as a tool that will someday be useful in the clinical assessment of auditory system structure and function. At this time, diagnosis of APD is based on the outcomes of behavioral tests, supplemented by electroacoustic measures and, to a lesser extent, by electrophysiologic measures.1

Behavioral assessment begins with a basic audiologic evaluation consisting of pure-tone audiometry, immittance measures, and speech-recognition testing (i.e., performance-intensity functions for word recognition). Otoacoustic emissions (OAE) measurement can be used to rule out inner ear disorders and is, therefore, a strongly recommended component of the basic evaluation. While the presence of mild-to-moderate peripheral hearing loss confirmed by the basic audiologic evaluation does not preclude evaluation of the central auditory nervous system, care must be taken in selecting auditory processing tests and in interpreting outcomes in the presence of peripheral hearing impairment.4

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9 What about the tests directly related to auditory processing?

Evaluation of auditory processing requires administration of multiple tests spanning the auditory processes described earlier in our conversation (i.e., sound localization and lateralization; auditory discrimination; auditory pattern recognition; temporal aspects of audition, including temporal resolution, temporal masking, temporal integration, and temporal ordering; auditory performance with competing acoustic signals; and auditory performance with degraded acoustic signals). This approach provides information as to the nature of the APD (i.e., which processes are deficient) and guides intervention planning and implementation.

Since our focus is on audition, we must select tests that employ tasks that control linguistic variables, i.e., stimuli with minimal or no linguistic demand or those with systematically manipulated linguistic variables.1 Likewise, it is important to minimize memory load and employ a simple response mode to minimize the confounding effects of speech production, sensorimotor, and motor learning problems.1 By controlling these variables, we are able to differentiate APD from performance deficits related to language processing, cognition, or motor control and learning.

My recommended test battery is similar (but not identical) to the minimal test battery described in the Bruton consensus paper.1 I would suggest that the audiologist include at least one measure from each of the following categories: (1) temporal processing (e.g., pitch or duration pattern perception, gap detection); (2) binaural integration (e.g., dichotic listening for digits, words, or sentences); and (3) monaural low-redundancy speech recognition (e.g., filtered or compressed speech, speech in competition). ABR and the middle latency response evoked potentials may supplement this behavioral battery.

Because these tests and procedures employ different tasks to measure different auditory processes, subjects may perform unevenly across tests. The audiologist must determine if the overall profile confirms APD. Diagnosis of APD on the basis of one failed test score should be made only if that score is at least three standard deviations below the mean performance for the subject's peer group.4 In such cases, it is helpful to re-test the subject to ascertain the reliability of that measure.

The Bruton consensus document also recommends several optional procedures that may confirm an APD. Specifically, one may administer analogous auditory and visual behavioral tasks (e.g., auditory and visual vigilance, auditory and visual element ordering) or event-related evoked potentials (e.g., P300) using auditory and visual stimuli presented within the “oddball paradigm.”1 Comparing analogous tasks across sensory modalities may help differentiate auditory-specific modality deficits (APD) from supramodal (e.g., cognitive) deficits and multisensory attention deficits (e.g., ADHD).1,52,5310 You say it is possible to evaluate auditory processing in the presence of peripheral hearing loss. How does one proceed? Two strategies will help in this case. First, it is important to realize that some auditory processing tests are influenced more than others by peripheral hearing loss. The greater the complexity of the intensity and frequency interactions, especially over a restricted time period, and the greater the demands placed on cochlear processing, the greater the peripheral influence.4

Dichotic CVs fit this profile. The resolution of fast intensity and frequency transitions underlies CV recognition. This resolution is heavily dependent upon cochlear processing. Consider the fact that individuals with sensory hearing loss experience difficulty recognizing CVs even when they are presented monotically. In contrast, steady-state pure tones, the stimuli used in the duration patterns test,54 are presented for a considerable duration and with a relatively long inter-stimulus interval. The duration patterns place far fewer demands on cochlear processing. Hence, individuals with sensory hearing loss generally perform better on the duration patterns test than they do on a dichotic CV test.

Therefore, when assessing auditory processing in the presence of peripheral hearing loss the audiologist should include tests that are more resistant to the effects of peripheral loss (e.g., duration patterns, P300).

A second strategy involves matching the test stimuli to normal regions of hearing sensitivity, where possible. For example, the duration patterns test is composed of 1000-Hz tones. Depending on the configuration of the hearing loss, one may be able to administer this auditory processing test at a frequency where hearing sensitivity is normal. This strategy may also work with other tests that employ low-to-mid-frequency stimuli (e.g., pitch patterns, low-to-mid-frequency tone pulses [gap detection]) that fall within the range of hearing that often remains normal in the most common types of cochlear hearing loss.

The presence of APD may sometimes be inferred from test outcomes. Specifically, the finding of dichotic test laterality (i.e., dominant ear effect) in the presence of bilaterally symmetrical hearing sensitivity and speech recognition would suggest APD. Likewise, one could infer APD in cases of asymmetric hearing loss where the better ear in terms of hearing sensitivity and speech recognition performs more poorly on the APD test battery.

11 What about assessing auditory processing in a non-native speaker of English or with individuals with limited English proficiency?

As discussed earlier, the purpose of an auditory processing evaluation is to assess audition apart from language or cognitive skills. Controlling linguistic variables is always of concern, but especially when assessing subjects with limited language experience or language sophistication (i.e., children).

When assessing non-native speakers of English, we must employ stimuli that pose minimal (if any) linguistic demand in English. An appropriate test battery might include behavioral tests and electrophysiologic procedures that rely on tonal stimuli (e.g., frequency and duration patterns, temporal gap detection, masking level differences, evoked potentials) or at least those requiring minimal facility with English (e.g., digits, CVs).55 Moreover, it is important that the subject understand the task instructions before being tested.

A few tests have been developed or translated in various languages, including Hebrew, Portuguese, Russian, and Spanish.56-58 The reader should be cautioned, however, that translated tests may not be equivalent to the original English version in difficulty level or efficiency and should be renormed prior to clinical use.55 Even dialectical differences must be considered when Spanish tests are administered to subjects from different backgrounds and nationalities. Clearly, much work lies ahead if we are to accurately assess APD in our increasingly diverse clientele.

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12 Aren't some of these tests too difficult for young children with normal auditory processing function?

Given the difficulty of the tasks, I would say that generally subjects must be at least 7 years old if the data derived are to be considered valid and definitive. A few instruments, such as the Pediatric Speech Intelligibility test, the SCAN-C, the Auditory Continuous Performance Test, and the Auditory Fusion Test-Revised, may provide some information for children younger than age 7 years.59-62 Limited data suggest that electrophysiologic procedures (MLR, P300, MMN) may prove useful in assessing very young children.55,79 Of course, the ABR and acoustic reflex studies may also offer insight regarding brainstem function in this population.

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13 Is there a screening tool available to determine which individuals are at risk for APD and refer them for more extensive audiologic evaluation?

There are several tools that purport to determine which individuals should be referred for APD testing. However, many of these screening instruments and questionnaires lack sensitivity. Moreover, these tools have often been misused to identify APD rather than to refer for assessment. As you know, screening instruments do not identify or label individuals, in this case, as APD. Rather, screening tools should be used to refer individuals for comprehensive diagnostic testing. Only then can one identify or attribute the label APD to an individual.

Given concerns regarding the sensitivity and, to a lesser extent, the specificity of these tools, it has been suggested that new screening tools be developed.1 In the meantime, audiologists may consider using a dichotic digits test and a gap-detection test for screening APD.1 Development and validation of screening questionnaires are also needed. Items should query behaviors commonly observed in association with APD and clearly defined pass/refer criteria must be provided.

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14 It seems that APD is often associated with communication, language, attention, and learning problems. Is it possible to sort out these various diagnoses?

This is a good, and somewhat difficult, question. But I will do my best to respond. What you are asking, essentially, is whether we can differentially diagnose APD. My answer is yes, although not without difficulty, especially given the overlapping clinical profiles we have discussed. A child can present APD in the absence of other deficits. It is also rather common to find several of these disorders co-occurring (i.e., co-morbid) in an individual. Also within the realm of possibility is that these co-morbid disorders are all related to some other underlying deficit. And, some might even argue that we are dealing with semantics—that we are applying different labels to describe the same symptomatology.

Clearly, then, a team approach to assessment is crucial to differential diagnosis. And, I would emphasize, one member of the team should be designated as the team leader. The leader is responsible for ensuring that all evaluations from the various specialties are conducted and for compiling the data and coordinating the team, particularly in ensuring that this differential diagnosis—or possibly multiple (co-morbid) diagnoses—leads to appropriate management planning.

As we have discussed, many listener variables (e.g., peripheral hearing sensitivity, native language and language experience and age, medications, attention) and task variables (cognitive demands, linguistic demands, response mode, learning and/or practice effects, etc.) known to influence performance on tests of auditory processing must be considered to properly differentiate disorders. Computer-controlled adaptive psychophysical procedures may maximize test efficiency and minimize floor and ceiling effects.1 Comparison of analogous tasks across multisensory modalities (e.g., auditory and visual sequencing or vigilance) is also helpful. Consideration of these variables will maximize the sometimes subtle differences between APD's auditory modality specificity and inattention purportedly seen across modalities in ADHD. Similarly, these strategies will assist in distinguishing language deficits from APD and visual-motor and memory deficits as well.

15 Wait a minute. What do you mean by multiple diagnoses? Are multiple diagnoses an excuse or apology for failure to differentiate diagnoses?

Well, the incorrect assignment of multiple diagnostic labels to an individual who actually presents with a single disorder would be a misuse of diagnostic labels. However, my point is that it is not uncommon for a child's symptomatology and test battery results to suggest more than one underlying disorder. Perhaps among the most common co-morbid diagnoses associated with APD are LD and ADHD.52,63

Audiologists and other members of the multidisciplinary team must be careful to assign a diagnosis only after a careful review of all results of the comprehensive battery of tests and systematic observation of the child. Failure to do so could lead to misdiagnosis, including the presumption of multiple disorders when only one exists.

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16 Once we learn that someone has APD, then what?

There are a number of approaches to managing and treating APD. I emphasize treating APD because we see accumulating literature documenting the efficacy of interventions that actually improve auditory processing, rather than offering only coping and compensatory approaches. I will address efficacy later. But, allow me to continue here by advocating a comprehensive intervention approach, employing a number of strategies.

There are several reasons we advocate a comprehensive plan. First, if our intervention goals are to improve listening and spoken language comprehension, then a multistrategy approach is needed to address the complex nature of auditory processing and listening.

Second, effective listening requires the orchestration of multiple knowledge bases and skills and information-processing strategies or styles. Some of these skills can be seen as bottom-up—for example discrimination, decoding, and segmentation; others invoke higher-level, top-down knowledge and processes, such as language, memory, and executive function. In fact, we expect that the top-down allocation of resources will influence bottom-up, perceptual events.10,13 Therefore, it is essential to approach manage-ment of APD from both the perceptual, bottom-up, auditory training direction and the cognitive, top-down, central resources direction.

Third, the efficacy of our interventions depends on generalization, which requires that new skills be integrated into one's everyday activity and lifestyle.4,64–66 Generalization, in turn, requires intact executive processing to guide the selection and monitoring of strategies.

Fourth, metacognitive, executive strategies will not only promote generalization, but they should also reduce the functional language and academic deficits frequently seen in individuals with APD.

For all these reasons, I believe it is important to follow a three-pronged approach to intervention for APD: Improve the quality of the acoustic signal and the listening environment, improve auditory skills, and enhance utilization of metacognitive and language resources.4

Of course, implementing these interventions requires a team of professionals collaborating with children, their families, and their teachers. The actual intervention program would be guided by the results of the audiologic test battery in the context of the multidisciplinary evaluations (i.e., language, psychoeducational) and the case history. Allow me to outline each prong of this comprehensive approach.

(1) The quality of the acoustic signal is most commonly enhanced using assistive listening technology such as a personal FM or sound field FM system.67 While FM technology may not be recommended in every case of APD, it is a cornerstone of our intervention with a large percentage of this population. Modifying the listening environment to improve signal reception often involves rather simple and typically inexpensive modifications, such as preferential seating, use of various furnishings and arrangements of furniture, wall hangings, etc. to reduce background noise and reverberation.68,69 Similarly, attention to lighting and visual aids will enhance the contribution of vision and the integration of audition and vision to benefit listening.

(2) Auditory skills training (AT) includes informal techniques (i.e., less acoustically controlled, more language-based techniques that may be conducted in the clinic, school, or home) as well as formal techniques that employ rigorous acoustic control, typically using tones and simple speech elements as stimuli.70 Formal AT would likely be administered by the audiologist or speech-language pathologist in the clinic. AT might target any number of skills, including frequency, intensity, and duration discrimination; temporal gap detection; temporal order discrimination; and dichotic syllable recognition, to name a few. For example, formal AT to improve temporal processing might target gap detection and ordering of two or three rapidly presented acoustic elements. An informal approach to temporal processing training might involve prosody training with heteronyms (e.g., subject vs subject) or ambiguous (i.e., temporally cued) sentences (“They saw the snow drift/snowdrift by the window”) or even recognition of time-compressed speech.71,72

(3) A number of metalinguistic strategies (i.e., strategies that focus on the ability to reflect on aspects of language apart from its content) also benefit listening and spoken language processing, These include schema induction (i.e., discovery of a structured cluster of concepts and expectations), context-derived vocabulary building, and the use of prosody and temporal cueing, as I just mentioned. Metacognitive strategies include attribution retraining, cognitive behavior modification (e.g., self-instruction, problem solving, self-regulation), and reciprocal teaching. I refer the reader to Chermak and Musiek for a detailed review of all the strategies mentioned here.4

17 What about the efficacy of the comprehensive approach you describe?

I am pleased to report that a rather impressive array of data from both animal and human studies reveals the potential of behavioral interventions to improve auditory processing and, in turn, listening and spoken language processing.

Let me reference some of the human studies. First, we have a number of studies underscoring the benefit of FM systems for listening and learning.73,74 (See Rosenberg and Blake-Rahter75 for a review.) Other studies focus on the benefits of auditory skills training70,76–79and the role of auditory-language training.80,81 Many studies have demonstrated the benefits of metacognitive and metalinguistic interventions for listening, learning, reading, and self-control.82-90

Despite the accumulating data suggesting the efficacy of a number of the component strategies and techniques I have outlined, it is crucial that clinical audiologists and speech-language pathologists collaborate with clinical scientists and researchers to ultimately determine the efficacy of the various approaches proposed to treat/manage APD. Until then, readers should consider my views expressed here as just that—my best recommendations based on my opinion, clinical experience, and interpretation of the literature.

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18 Can you tell us about the use of medication and computerized therapy tools in treating APD?

A number of studies have demonstrated that pharmacologic intervention can alter physiologic and behavioral aspects of audition.91-94 Studies have also demonstrated the beneficial effects of methylphenidate (i.e., Ritalin) in reducing hyperactivity, impulsivity, and distractibility in children diagnosed with ADHD.95 However, whether or not methylphenidate improves auditory processing is much less certain. The few published studies that have directly approached this question suffer from a number of limitations, including small sample size, variable subject selection criteria, use of less efficient dependent measures, and learning effects.96-98 With this qualification, I can report that some studies found improvements on auditory tests in the methylphenidate condition in children diagnosed with ADHD98 and in children diagnosed with ADHD and APD.96,97

In contrast, in a very well-designed study involving children diagnosed with APD and ADHD, no change was reported in several auditory processing measures (with the exception of auditory vigilance) in the medicated (methylphe-nidate) condition relative to the non-medicated state.99 Improvement in auditory vigilance was not unexpected given the known improvements in impulse control and reduced distractibility in children given stimulant medications.95 Tillery et al.'s finding of improved auditory vigilance may reflect more on the ADHD than the APD.99 In fact, another study found no significant difference in auditory vigilance between subjects with ADHD alone and those with ADHD and APD.100

I am often asked whether audiologists should assess the auditory processing abilities of children diagnosed with ADHD while they are on or off their medication. Although I see no evidence in the literature to confirm that methylphenidate improves auditory processing, I think it is still important to assess these children following the prescribed medication schedule. Doing so allows us to take advantage of the medication's positive effects on impulse control and attention, thus maximazing cooperation and persistence on task, and reducing stress on the child and the tester!52 Periodic breaks and consistent reinforcement should also prove helpful.101

Regarding computerized therapy tools, perhaps you have heard of Fast Forword or Earobics. The reports published in the literature I track certainly suggest that these tools are very promising. However, in my opinion, there have been too few peer-reviewed, published reports to really judge the efficacy of the existing software that purports to improve auditory processing and language processing in a number of clinical populations.80,81

In general, computer-mediated therapies hold great potential, as the computer is an engaging vehicle that allows for more intensive practice to reach mastery and automaticity. It appears that repeated stimulation, graduated in difficulty in a systematic fashion, is most likely to result in learning.102-104 I also feel that computer-mediated therapies should be coupled with experiential, functional activities to establish skills and strategies that generalize to real-world settings. I encourage clinicians and clinical scientists to employ computer-mediated therapy tools in controlled case studies and single-subject and group research designs to ascertain systematically the relative efficacy of these tools, as well as other approaches that we have discussed.

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19 I understand many children diagnosed with APD are ineligible for services in schools. Can you tell me why and offer options for children with APD and their parents?

Unfortunately, in too many states, a diagnosis of APD does not qualify children for school-based special services under the Individuals with Disabilities Education Act (IDEA). In some states, children with APD may qualify for services under the hearing impairment category due to a fluctuating hearing loss (often related to ROM) or because the category is construed broadly enough to include those with listening problems, which may or may not be related to a peripheral hearing loss.

In most states, children with APD can qualify for services on the basis of a co-morbid condition. Most often this co-morbid diagnosis is specific learning disability. Sometimes the dual diagnosis of ADHD qualifies children with APD under the health impairment category. For children with APD who do not qualify under these other categories, one may argue for services under the Americans with Disabilities Act (ADA) and Section 504 of the Rehabilitation Act of 1973.

In contrast to IDEA, which is a funding law, the Rehabilitation Act of 1973 is a civil rights law that prohibits agencies receiving federal funds from discriminating against otherwise qualified individuals simply on the basis of the disability. Similarly, the ADA is a comprehensive civil rights law that ensures people with disabilities access to all facets of American society. The ADA is broader than the Rehabilitation Act, offering protections in both the public and private sectors in employment, state and local government (including the public school system), public accommodations, and telecommunications. If it is determined that a youngster with APD experiences difficulty in learning, Section 504 and the ADA can be used to argue for either special education services or regular education services with necessary adaptations and interventions to ensure access to an appropriate education.

Section 504 and the ADA entitle children with disabilities, regardless of the nature, diagnosis, or severity of the disabilities, to full and equal educational opportunities and access.105 In essence, children with APD need not meet specific eligibility criteria for educational services under Section 504 or the ADA. Children who do not qualify for services under IDEA may still be eligible for services on the basis of the protections afforded by Section 504 and the ADA.

The audiologist and other members of the team must document convincingly that a child has hearing and listening problems that limit the child's acoustic access to instruction. At a minimum, this child may require assistive technology to achieve access to auditory information and an appropriate public education.105 This is the view from the ivory tower. Parents and my colleagues in the schools tell me that it is often quite difficult to work through all of this.

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20 So, as a profession, do you really think we can make a difference in APD?

My response is a resounding yes—and a significant difference at that.

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