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15 Auditory Neurophysiology of Reading Impairment: Theory and Management

Madell et al., Pediatric Audiology: Diagnosis, Technology, and Management, 3rd Ed. (ISBN 978-1-62623-401-7), copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.

of speech sounds and language. We hope, however, to have illustrated that audiologists have an important role as well. Objective measures of auditory function identify children with RI, predict which children are at risk for RI, and track outcomes following intervention. Audiologists have the unique skill set necessary to conduct tests such as the FFR. One can envision a day when, in addition to hearing screening, newborns receive a hearing brain screening to identify risk for language and reading problems.

Pearl

Audiologists can join speech-language pathologists and psychologists as part of a multidisciplinary team to manage RI.

Discussion Questions

1. What are three pieces of evidence that auditory processing

is disrupted in poor readers, and which theories of reading impairment does this evidence map on to?

2. How can changes in auditory processing be objectively monitored, and how do these changes relate to improved reading skills?

3. For each of the FFR protocols presented in this chapter, describe a patient for whom FFR would be an appropriate evaluation, and discuss how positive and negative results would be interpreted.

Acknowledgments

The research in this chapter has been supported by NIH (R01

HD069414) and the Knowles Hearing Center.

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[65] White-Schwoch T, Davies EC, Thompson EC, et al. Auditory-neurophysiological

responses to speech during early childhood: Eects of background noise. Hear Res 2015;328:34–47

[66] Skoe E, Nicol T, Kraus N. Cross-phaseogram: objective neural index of speech

sound dierentiation. J Neurosci Methods 2011;196(2):308–317

[67] White-Schwoch T, Kraus N. Physiologic discrimination of stop consonants relates

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[68] Skoe E, Krizman J, Anderson S, Kraus N. Stability and plasticity of auditory brain-

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[69] American Speech-Language-Hearing Association Working Group on Auditory

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http://www.asha.org/policy/TR2005-00043/. 2005. Accessed December 21, 2017

[70] Warrier CM, Johnson KL, Hayes EA, Nicol T, Kraus N. Learning impaired children

exhibit timing deﬁcits and training-related improvements in auditory cortical responses to speech in noise. Exp Brain Res 2004;157(4):431–441

[71] Russo NM, Nicol TG, Zecker SG, Hayes EA, Kraus N. Auditory training improves

neural timing in the human brainstem. Behav Brain Res 2005;156(1):95–103

[72] Strait DL, Parbery-Clark A, O’Connell S, Kraus N. Biological impact of preschool

music classes on processing speech in noise. Dev Cogn Neurosci 2013;6:51–60

[73] Kraus N, Slater J, Thompson EC, et al. Music enrichment programs improve the

neural encoding of speech in at-risk children. J Neurosci 2014;34(36):11913– 11918

[74] Kraus N, Anderson S. Auditory processing disorder: biological basis and treat-

ment ecacy. In: Le Prell CG, Lobarinas E, Popper AN, Fay RR, eds. Translational

Reserach in Audiology, Neuro-Otology, and the Hearing Sciences. Springer Hand-

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Anderson S, Parbery-Clark A, White-Schwoch T, Kraus N. Development

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of subcortical speech representation in human infants. J Acoust Soc Am

2015;137(6):3346–3355

Suggested Additional Readings

[1] Bishop DVM. Uncommon Understanding: Development and Disorders of Lan-

guage in Children. New York, NY: Psychology Press; 1997

[2] Dehaene S. Reading in the Brain: The New Science of How We Read. New York,

NY: Penguin Books; 2009

[3] Kraus N, Anderson S, White-Schwoch T, Fay RR, Popper NN, eds. The Frequen-

cy-Following Response: A Window into Human Communication. New York, NY:

Springer-Nature; 2017

[4] Shaywitz SE. Overcoming Dyslexia: A New and Complete Science-Based Program

for Reading Problems at Any Level. New York, NY: Vintage Books; 2003

[5] Resources on the FFR, including stimuli, software, and video demonstrations, are

available online at http://www.brainvolts.northwestern.edu

172

16 Assessment, Treatment, and Management of Auditory Processing Disorders in Children

16 Assessment, Treatment, and Management of Auditory

Processing Disorders in Children

Gail M. Whitelaw

Summary

This chapter focuses on the assessment, treatment, and management of auditory processing disorders in children. The history of auditory processing disorders in the profession of audiology is

briey addressed; however, the focus is on the current and future

aspects of auditory processing disorders as part of the scope of

practice of audiologists. If audiologists are to “own” the auditory

system, they must be comfortable with looking at hearing and listening needs that go beyond the results obtained on an audiogram,

and the chapter focuses on how to look beyond the “detection”

of sound to quantify hearing and listening. Auditory processing and its disorders are described in order to put parameters on working with children who are referred for auditory processing disorder assessment. Interdisciplinary team considerations to support information needs are also addressed. Recommendations for developing assessment parameters and for creating con-

siderations for a test battery are oered. Interaction between

development and assessment of auditory processing skills is

described. The “myth” that there is nothing that can be done to address auditory processing deﬁcits is also addressed, with a focus

on capitalizing on the plasticity of the auditory system to improve skills provided. Technology options, including use of hearing aids and remote microphones, are discussed. Current auditory training options are reviewed. Additional treatment/management options are provided, including how these may be incorporated into the

Individualized Education Program/504 process for school-aged

children. The future of assessment and treatment of auditory processing disorders is described, based on current research.

Keywords

auditory processing disorders, test battery, interdisciplinary team, remote microphones, auditory training

Key Points

Auditory processing disorders are considered on the contin-

•

uum of auditory disorders that includes peripheral hearing loss. Many children with auditory processing disorders expe-

rience signicant functional communication impairment.

Assessment of auditory processing disorders is in the scope of

•

practice of the audiologist, although interdisciplinary input is

necessary for eective diagnosis and treatment.

Peripheral hearing loss must be ruled out in any situation

•

where a listening problem is suspected; it is critical to address the concerns expressed by the parents regarding their child’s hearing and listening skills. A test battery approach must be used to assess auditory pro-

•

cessing disorders eectively; however, a gold standard has

not been established for evaluation of auditory processing disorders. Considerations should include the purpose of the

assessment (e.g., educational or dierential diagnosis), the

referral source, and the assessment of outcomes of treatment programs. Assessment of auditory processing skills can use either

•

behavioral or electrophysiologic methods; the same goal is present regardless of the testing, which is to tax the auditory system in order to challenge the child’s listening skills. Management and treatment of auditory processing disorders

•

focuses on three areas: modifying the listening environment, developing compensatory skills, and providing treatment directed at the auditory system. Current technology provides a strong support for APDs

•

in children. Options include personal remote microphone technology, hearing aids, and classroom audio distribution systems. Current auditory training programs take auditory develop-

•

ment into account and use adaptive methods to challenge the auditory system.

16.1 Introduction to Assessment, Treatment, and Management of Processing Disorders

Consider the following scenario. A school-aged child presents at an audiology clinic with parent- and teacher-reported concerns about the child’s diculty hearing and listening when competing auditory information is present. Using the medical school

adage “when you hear hoofbeats, think horses rather than zebras,” the audiologist performing the evaluation is likely to

look for the most common explanation for the reported concerns and suspect cochlear hearing loss. However, this child also has a long-standing inconsistency in responding to auditory infor-

mation and following speech when presented at a “typical” rate.

The parents report that these behaviors have been present since the child was a preschooler, and describe them as subtle, yet the

behaviors have a signiﬁcant impact on the child’s listening and

learning. The audiologist may then consider a greater range of potential explanations and etiologies, such as the possibility of

a unilateral hearing loss or a “minimal” hearing loss. In addition,

the audiologist may consider mild or high-frequency hearing loss or possibly a uctuant conductive hearing loss. A range of nonaudiologic factors may also be considered, such as attention issues, cognitive impairment, and/or learning disability. The question arises: If the presenting concerns were hearing and listening and the results of the conventional audiometric evaluation are consistent with normal peripheral hearing acuity and good word recognition skills, is the work of the audiologist complete? Some audiologists would assert that they have answered the question at hand: the child has “normal hearing.” However, when auditory concerns are reported in the face of a normal audiogram and typical cognitive and learning abilities, the presence of an

173

II Diagnosing Hearing Disorders in Infants and Children

auditory processing disorder (APD) must be considered. In the

past, APD may have been more of a “zebra” when hoofbeats were

heard. However, current interest in cognition and listening has resulted in APD becoming more of a mainstream consideration in children.

Assessment, treatment, and management of auditory processing disorders in the pediatric population constitute one of the most exciting, challenging, and controversial areas in audiology.1 Understanding the clinical diagnosis of APD requires the audiologist to consider information beyond that obtained on the audiogram, to develop an interdisciplinary perspective, and to apply knowledge across a broad range of domains including auditory development, classroom acoustics, and aural rehabilitation.

Mykelbust ﬁrst described APDs in children, although he referred to them as “auditory imperceptions.”2 Since that time, a constellation of deﬁcits that may contribute to auditory processing diculties has received many labels, including “auditory comprehension deﬁcits,” “central auditory dysfunction,” “central deafness,” and “word deafness.”3 The current term is “(central) auditory processing disorder” ([C]APD). “hidden hearing loss” in children has been introduced, describing

developmental APD as a multifaceted developmental disability.

APD is not a new area in the profession of audiology, nor is it a topic unique to audiology. Behaviors and skills such as attention, memory, and global sensory issues have been attributed to the auditory system, and other professions may diagnose and treat these disorders with little understanding of the auditory system or its development. It is not unusual for a child to be labeled with

an “auditory processing problem” by an occupational therapist

or psychologist, despite the fact that diagnosing and treating disorders of the auditory system are not in the scope of practice of those professions. This particularly adds confusion when behaviors are attributed to children on the autism spectrum that are part of a global processing disorder rather than related solely to the auditory system. orders without a thorough understanding of the auditory system

further complicates issues of deﬁning the disorders, resulting in misidentiﬁcation of children and their placement in treatment

programs with no evidence base, causing an expenditure of time and resources on the part of the child, the family, and the school

with no demonstrated improvement in “auditory processing.”

Clearly, the diagnosis and treatment of APDs are in the scope of practice of the audiologist4; the audiologist “owns” the auditory system from pinna to auditory cortex. Not every audiologist needs to assess or treat APD; however, every audiologist should be aware of APD and know when to make an appropriate referral for APD assessment. The American Speech-Language-Hearing Association (ASHA)10 states that the audiologist is responsible for the evaluation and management of children who demonstrate auditory-

related processing disorders. In addition, APD is not identiﬁed or

treated in isolation and requires input from a range of disciplines, including speech-language pathology, occupational therapy, physical therapy, neuropsychology, pediatrics, and optometry, to name a few. In addition, input from parents, teachers, and the

child is critical for eective assessment and treatment. Knowledge

of the auditory system, the ability to control stimulus presentation, the ability to control the environment in which assessment is performed, and skills in the area of aural rehabilitation make the

audiologist uniquely qualiﬁed to address APDs in children.

7,8

Identiﬁcation of auditory processing dis-

4,5

Recently, the concept of

The purpose of this chapter is to provide an introduction to broad concepts related to APD and to whet the reader’s appetite to learn more in this area. Current issues related to APD are discussed, along with an overview of contemporary approaches to the diagnosis and treatment of APD in the pediatric population. It is assumed that the reader accepts APD as a clinical entity, based on current research and inclusion of APD in the International

Classication of Diseases and Related Health Problems, 10th Revision (ICD-10, coded as H93.25).

view APD on a continuum of auditory disorders that aect communication and education. The types of diculties experienced

by a child with APD share similarities with peripheral hearing loss in that they present as an invisible disorder that may impact the development of speech-language skills, academic achievement, and listening abilities. However, APD may have a more subtle presentation than hearing loss. In addition, the audiologist faced with assessing and treating APD is often part of a team providing a

dierential diagnosis and developing a treatment plan; behaviors

reported as consistent with APD may often be observed in other types of disorders, such as autism spectrum disorders (ASD) or

attention-deﬁcit/hyperactivity disorder (ADHD).

This chapter focuses on both historic and current perspectives in the evaluation and treatment of APD in children. The most exciting aspects are related to future implications of current research in auditory processing. Advancements in neuroscience and functional imaging of the auditory system are two of many areas that are generating a more thorough understanding of the central auditory nervous system. These discoveries are leading to better assessment protocols and techniques and to new approaches to treatment and management of APDs.

11,12

The reader is challenged to

16.2 A Conceptual Framework for

Auditory Processing

Pitfall

Despite the fact that interest in APD has existed for decades, pro-

viding a clear and concise framework for dening these disorders

remains controversial in the profession of audiology.

For many years, deﬁnitions of APD were criticized for being too lax, not modality speciﬁc, and not able to be distinguished from other areas of deﬁcits including peripheral hearing loss, cognitive, language, and attention deﬁcits.

professions, such as psychology and occupational therapy, use

the term “auditory processing”; however, the term applies to a more global set of behaviors, further confusing the deﬁnition. Conversely, some audiologists doubt the existence of deﬁcits

that arise from the auditory system as explanations for certain behaviors, attributing these behaviors instead to disorders of nonauditory modalities such as attention or language.

Although there is no generally accepted comprehensive deﬁnition of APD, the challenges of the past have led the profession

to update deﬁnitions to address, at least in part, these criticisms. ASHA deﬁnes auditory processing as “the perceptual processing

In addition, other

174

16 Assessment, Treatment, and Management of Auditory Processing Disorders in Children

of auditory information in the CNS [central nervous system] and the neurobiologic activity that underlies the processing and gives

rise to electrophysiologic auditory potentials,”14 in which APD is a disorder. Similarly, APD was deﬁned in the recommendations of the Burton conference as a “deﬁcit in the processing of information in the auditory modality.”15 A critical issue that is not raised in either of these deﬁnitions but must be stated implicitly is that APD reects deﬁcits “in the formation and processing of audible

signals not attributed to impaired hearing sensitivity or intellec-

tual impairment,” thus not attributed to peripheral hearing loss

or cognitive disorders.16 A simple yet functional description of an APD is a breakdown in auditory abilities resulting in diminished learning, comprehension, or both of auditory information through hearing, although peripheral hearing sensitivity is within normal limits. For the purposes of this description, normal hearing should

be considered as detection thresholds of 15 dB hearing level (HL)

or better by conventional audiometry for both ears, which has his-

torically been referred to as the “low fence” for hearing in children.

As noted in the British Society of Audiology Position Statement on

Auditory Processing Disorder (APD), “listening” is a term used in

auditory processing as an active process, while hearing implies a more passive process.5 Despite controversies that persist in the area of auditory processing, years of evidence establish APD as a

“true” clinical disorder.

Auditory processes may be described as the auditory system mechanisms responsible for the following behaviors: sound localization and lateralization, auditory discrimination, temporal aspects of audition, auditory performance decrements when competing acoustic information is present, and auditory performance decrements when the auditory signal is degraded.17 APDs may be present for both speech and nonspeech stimuli.5 These types

of deﬁcits result in the auditory system being less exible than required for eective listening in a wide variety of environments

faced by most children each day. This is particularly true in the classroom environment, where unfamiliar linguistic information is being introduced in a less than optimal acoustic environment. Poor acoustic accessibility taxes an auditory system that cannot

eectively rise to the challenge of listening, particularly in a less

than optimal environment. APD results in a reduced ability to listen and persistent limitations in performing auditory activities,

having signiﬁcant impact on listening performance in everyday

5,18

tasks.

A strict deﬁnition of APD has clinical relevance. APD can be a “ﬁeld of dreams” for families looking for answers, when applied in its broadest deﬁnition. Parents or educators who are shopping for

explanation of academic underachievement may cling to APD as a holy grail, since they may ﬁnd APD to be a more palatable diagnosis than other possible options, such as cognitive impairment, learning disabilities, or ASD. The ready availability of information and misinformation on the Internet regarding auditory processing also fuels referrals for testing. The audiologist must base decision making about auditory processing assessment on as strict a deﬁnition available in order to minimize inappropriate referrals and

to use time and resources most eectively.

APD is considered to be a low-incidence disorder, because a relatively small number of children are thought to have this type of exclusive condition. The prevalence of APD is estimated as 2 to

10% in school-aged children.

11,19

APD is considered idiosyncratic

due to individual organizational abnormalities that are subtle yet

with diverse presentations; therefore, APD can be as idiosyncratic as the individuals who experience it.

A child may have an acquired APD, based on a known event such as a concussion; however, in most cases, APD is developmental, where the actual etiology is generally unknown, and thought to have origins in impaired neural function.5 Delays in auditory development related to factors such as chronic otitis media have also been considered, with delays in the development of binaural hearing most frequently cited in children with this

21,22

history.

Recent evidence has demonstrated what has been long

speculated: that there is a genetic basis for at least some types of

11,23

APD.

It is important to recognize that the processing of auditory information within the central auditory nervous system (CANS) is complex, involving both serial and parallel processing within the CANS as well as processing that is shared with other brain structures and systems, including those that govern language processing, attention, and executive control.4 These interactions underline the fact that the brain is not compartmentalized and that the dysfunction does not respect functional boundaries of

the brain and may not merely reect a “bottom-up” impairment

of the auditory system.

6,20

With this said, it is not surprising that behavioral manifestations and levels of impairment in children with APD are diverse and heterogeneous.

As noted previously, APD should be considered on the continuum of hearing loss, and many of the behaviors noted in children with APD are similar to those in children with peripheral hearing loss,

such as diculty listening in the presence of background noise. A

frequent question is related to assessing auditory processing skills in children with known peripheral hearing loss. As established

in this chapter, a generally accepted deﬁnition of APD identiﬁes deﬁcits in listening in the presence of normal peripheral hearing acuity. By deﬁnition, children with peripheral hearing losses would be expected to have diculty with the processing of auditory infor-

mation based on the nature of hearing loss alone. As established by Erber, there is a hierarchy of auditory skills predicated on detection, or audibility, of sound. If audibility is compromised, as is the case

with peripheral hearing loss, the child will experience diculty with higher-level tasks, such as discrimination, identiﬁcation, and

comprehension of sound. If the question arises about auditory

processing deﬁcits in children with hearing loss, the motivation for

the question should be explored. Issues that should be addressed in this case should include monitoring of peripheral hearing loss for progression; measuring speech-in-noise abilities with hearing aids/ cochlear implant; obtaining real-ear measures to ensure audibility; history of auditory-based therapy; and performing functional listening evaluations.

Assessment of an APD in a child with hearing loss is controversial and must be approached cautiously. The potential negative impact of peripheral hearing loss on the evaluation of auditory processing skills has been well established.25 The auditory pro-

cessing skills of children with signiﬁcant degrees of peripheral

hearing loss cannot be accurately assessed; however, those with mild degrees of hearing loss and good word recognition skills

may be potentially assessed with tests that are less inuenced by

the presence of cochlear hearing loss, such as the dichotic digits test.4 Some tests that may be included in a behavioral test battery, such as the SCAN-3: Tests for Auditory Processing Disorders in

Children, provide speciﬁc cautions and caveats regarding testing

children with peripheral hearing loss. The relationship between

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II Diagnosing Hearing Disorders in Infants and Children

peripheral hearing loss and auditory processing is complex; this

relationship is recognized in the deﬁnition of secondary APD. In

this case, the APD may occur as the result of a peripheral hearing loss, including transient hearing loss as the result of chronic otitis media.5 Based on the current state of the science, assessment of APD in children is best reserved for those for whom peripheral hearing is known to be normal. If a concern regarding hearing or listening is noted, a comprehensive evaluation of hearing should be performed, particularly since a subset of children referred for auditory processing assessment have an undetected hearing loss responsible for listening concerns. Additionally, a comprehensive assessment of listening skills in children with hearing loss should be performed, as outlined in Chapters 9 and 29 of this book.

16.3 Assessment of Auditory Processing Skills in Children

The challenge of assessment of auditory processing is to develop a comprehensive test battery that provides adequate information

in a time-ecient manner to describe the functional parameters of the child’s skills across a variety of auditory behaviors; oers a

diagnosis; and guides appropriate treatment and management.26 Historically, assessment of auditory processing skills arose from the experience of adults who presented with listening diculties in less than optimal environments, despite having normal peripheral hearing acuity. Sensitized speech testing, which reduced the intelligibility of the speech signal by distorting it

acoustically (as by ﬁltering out the high frequencies needed for

distinguishing consonants or by compressing the dynamic range) or introducing noise, were used to challenge the auditory system as part of a site-of-lesion assessment in adults with pathologies of the CANS.27 Several tests, using various methods of distorting the signal and challenging the auditory system, were developed during this period, including the Staggered Spondaic Word (SSW) test28 and the Dichotic-Consonant/Vowel (D-CV) test,29 and are still used today. These tests were designed to be sensitive to detecting retrocochlear and central pathologies in adults.

Some children with normal peripheral hearing acuity had listen-

ing deﬁcits that were similar to those demonstrated by adults with

known CANS lesions. An interest in exploring these similarities

coincided with the introduction of the term “learning disabilities” into the realm of public education during the 1970s, along with the

subsequent explosion in programs targeted at remedying learning disabilities, with a particular focus on processing and perceptual training.30 Whether or where APD ﬁts into a continuum of learning disabilities is a discussion that continues today, as classifying APD as an educationally handicapping condition is a critical question.

Willeford introduced the ﬁrst tests designed speciﬁcally to assess

APD in school-aged children.31 Since that time, knowledge of auditory development and methods for assessing auditory skills in children have evolved, and materials and techniques available for assessing auditory processing skills in children have expanded.

Tests designed to assess auditory processing skills in children are based on several tenets. Assessment of auditory processing is based on the assumption that the internal or intrinsic redundancy of the CANS is somehow compromised as a function of disorder, delayed

development, or some type of neurological wiring dierence.

This intrinsic redundancy is responsible for the auditory system

being exible enough to ﬁll in missing information or to focus on

a primary message when a competing auditory signal is present. It is anticipated that tests be administered as part of a battery, and regardless of whether they are behavioral or electrophysiologic,

they be designed to “tax” or challenge the auditory system in a

unique way that manipulates an aspect of stimulus presentation.

An understanding of the role of auditory development in the assessment of auditory processing evaluation is critical. All auditory processes demonstrate a developmental component, and for some processes, development continues well into adolescence. It is well established that children demonstrate poorer listening abilities than adults in terms of a variety of auditory behaviors, and they require a more favorable listening environment for performing auditory tasks than adults do. are greater than those that can be explained by attention and motivation of the listener alone and have been attributed to the

ongoing maturation of the CANS. It is critical that these dierences

be taken into consideration in developing an APD test battery in children that is based on current knowledge of auditory development and that normative data have been obtained across the age group for which the test is targeted. The reader is encouraged to review auditory development to be able to apply this information to auditory processes and APD assessment.

Although APD is best assessed and diagnosed in the realm of an interdisciplinary team, diagnosis and treatment are within the scope of practice of an audiologist. Auditory processing disorders cannot be diagnosed based on the results of testing administered by psychologists, occupational therapists, speech-language pathologists, or other professionals, even if the tests administered

include the terms “auditory” or “auditory processing” in their

title.4 Children are frequently identiﬁed as having an auditory processing disorder based on results of a test administered by a professional other than an audiologist, in a setting that lacks acoustic control (e.g., classroom), in a nonstandard manner (e.g., live voice presentation by the examiner; presentation of stimuli from a CD player that is not calibrated; or stimuli presented in

the soundﬁeld). An example of a frequently used test resulting in

the label of auditory processing disorder is the Test of Auditory Processing Skills-3 (TAPS-3),36 administered by professionals other

than audiologists. The test purports to address “what a person does with what they hear.” Although the TAPS-3 may be a strong

diagnostic tool for other types of issues, its use as a diagnostic tool

for the diagnosis of APD is awed. Control of the test environment,

stimulus, and test parameters are critical factors in obtaining accurate and valid assessment of auditory processing skills, as is true in any type of assessment of the auditory system. However, testing

in the ﬁeld or outside the booth with changes in technology is

clearly a growing trend, as seen in Shoebox Audiometry (Ottawa, Canada)37 or Acoustic Pioneer,38 and is laying the groundwork for how testing will be performed in the future.

32,33,34

These dierences

Pearl

The dierence between a developing auditory system and a disordered auditory system must be delineated as part of the test battery; however, both aspects are of interest to the pediatric audiologist.

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16 Assessment, Treatment, and Management of Auditory Processing Disorders in Children

16.3.1 Practical Considerations in Test Battery Selection

An audiologist new to the area of APD will often seek to create a

“cookbook” approach to testing, looking for a standard battery.

However, currently there is no gold standard for assessment of auditory processing. This lack of standardization of assessment results is a challenge in comparing the results of studies, evaluating best practices, and monitoring the development of auditory skills, even for an individual child. A complication is the diversity of philosophical approaches to APD, despite advances in adopt-

ing a more uniform deﬁnition. Phillips addressed this concern in stating, “in practice however, this is often the state of a young

science and any standardization of test materials that is appro-

priate will emerge as the scientiﬁc issues sort themselves out over time.”20 Development of newer materials and a standard test

battery is being explored for both children and adults, demonstrating a strong potential for clinical use in the near future.

Until a gold standard test battery is developed and agreed upon, audiologists assessing children for APD must rely on their knowledge and expertise, along with available research in the area, and select a test battery based on a number of factors, including the population to be tested, the audience for whom the testing is being performed (e.g., who is the referral source), and the purpose for which the information is requested (e.g., educational input or

dierential diagnosis). While the lack of a gold standard battery

may be viewed as a limitation of APD testing, a smorgasbord of tests available provides the audiologist with the opportunity to tailor an approach to assessment that addresses the presenting concern and to tailor the results of the assessment to advance the development of treatment and management approaches. The audiologist should consider the rationale for selection of each test and the unique contribution that the information obtained from that test will make to answering the questions raised in the referral for APD testing or the child’s presenting concerns. For example, tests that use a standard scoring method, such as the SCAN-3, may provide the ability to compare with the results of other standardized educational testing, so that the results of an auditory processing assessment can be contrasted to those results obtained in a speech-language or cognitive test battery.

39,40

Pearl

A guiding tenet must be that if there is a concern regarding hearing and/or listening skills, a comprehensive audiologic evaluation must be scheduled, regardless of the child’s age or other presenting issues, to ensure that the child does not have peripheral

hearing loss. A hearing screening alone is not sucient.

A prescreening procedure is beneﬁcial to ensure that the assessment of auditory processing skills is appropriate for the patient

g referred. Many practices establish criteria for scheduling

bein an auditory processing assessment. For example, the age criteria

of 7 years is typically established, and children younger than 7

will not be seen for a formal auditory processing assessment.

Before age 7, the auditory system demonstrates considerable

variability that impacts the administration and interpretation of auditory processing testing. An additional criterion is eliminating children with a history of peripheral hearing loss or cognitive

impairment or those who have been identiﬁed on the autism spectrum. Diculty in processing auditory information may be inherent in each of these diagnoses; however, these diculties are not speciﬁcally related to CANS dysfunction. The population of children identiﬁed on the autism spectrum continues to grow;

the questions of the relationship between ASD and APD continue

to be explored, with conicting ﬁndings reported.

must be involved in the team that contributes to this diagnosis by providing a comprehensive audiologic evaluation to children who are suspected to be on the autism spectrum.

41,42

Audiologists

Special Consideration

At this time, there is no evidence that children with ASD have a higher incidence of comorbidity of APD or the behaviors that are attributed to auditory perception, nor are they related to a more

global sensory decit than children in the general population

43,44,45

are.

A comprehensive case history should be considered the ﬁrst

test of the APD battery. Information should be obtained that addresses birth and developmental history; family history of communication disorders, learning disabilities, and hearing loss; medical history (including information about medications, head injury, and concussion); academic/educational history; social

and emotional development; and speciﬁc otologic questions

including information about tinnitus, hyperacusis, and balance. Records from previous assessments, including speech-language,

medical, and cognitive evaluations, are of signiﬁcant value in

understanding the child’s skills and in providing a broader view of understanding presenting concerns. The results of a MultiFactored Evaluation (MFE) and Individualized Education Program

(IEP) can provide signiﬁcant insight into academic strengths and

concerns and provide one mechanism of input from the school perspective. Additional information from school personnel, parents, and the student regarding hearing and listening concerns should be obtained by authentic assessment. Authentic assessment is designed to obtain information about functional hearing and listening skills in the real-world environment, validating the areas of concern. A number of questionnaires are available for the purpose of authentic assessment that are relatively quick to administer and have good validity.46 These tools include the Evaluation of Children’s Listening and Processing Skills [ECLiPS],46 the Children’s Auditory Processing Scale (CHAPs),47 the Screening Inventory for Targeting Educational Risk (SIFTER),48 and the Children’s Communication Checklist (CCC-2).49 Information gleaned from these tools highlights the importance of obtaining input from multiple perspectives in the assessment and interpretation of APD.

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II Diagnosing Hearing Disorders in Infants and Children

16.3.2 Behavioral Assessment

As noted by Emanuel et al,50 there is currently no gold standard for the selection of individual tests or a test battery to identify APD in children without a documented lesion of the auditory

system. Guidelines that outline auditory processing assessment

suggest that APD testing should be based on individual case history presentation and other individual factors; however, guidelines support that the test battery should be designed to

assess a range of auditory processes and to challenge dierent

areas of the CANS. vate the selection of tests. A survey of audiologists performing auditory processing assessment in children found that the most frequently utilized behavioral test were those that targeted dichotic listening skills, used monaural low-redundancy speech stimuli, and addressed temporal processing skills. is in keeping with recommendations of the ASHA position statement,17 which recommended including assessment of temporal processes (ordering, resolution, integration, and discrimination); localization and lateralization; low-redundancy monaural

speech (e.g., time-compressed, ﬁltered, interrupted, competing);

dichotic stimuli ranging across a number of linguistic levels, including consonant-vowel or nonsense syllables, digits, words, and sentences; and binaural interaction procedures. Many studies have addressed individual test performance in children; however, the development of test batteries (i.e., two or more tests)

as not been widely addressed.51 Recently, the combination of

low-redundancy monaural speech (e.g., low-pass ﬁltered speech [LPFS]) and temporal processing (e.g., speciﬁcally frequency

patterns) has been shown to have the highest failure rate for children with APD, suggesting these should be included in a test battery for children.52 Additional considerations in building a behavioral APD test battery would be to vary the linguistic load of the stimulus, including speech and nonspeech stimuli, using varying response modes, and challenging the auditory system in a variety of ways. The child’s subjective behavior while in the booth should be observed and incorporated into test interpretation.

This chapter will focus on the general categories of skills that may be assessed in a behavioral test battery, with characteristics

of each category briey highlighted here. Speciﬁc test materials

are included in Appendix 16.1. It should be noted that in selecting tests, the quality of the recording and strength of normative data development should be considered. A number of tests are available that have not been updated since their development and have c

learly used older recording techniques that result in considerable

background noise in the recording.

Tests of Temporal Processing

The importance of temporal aspects of audition is evident. Phillips noted that a vast number of auditory processes rely on temporal analysis of the incoming signal.20 Tallal and coworkers

reported that deﬁcits in temporal processing could contribute to deﬁcits in typical phonological development, thereby con-

tributing to disorders in reading and speech for at least a subpopulation of children. Tests in this category include presenting stimuli that address the listener’s abilities in temporal ordering, discrimination, resolution, and integration, as suggested by

4,14,18

Presenting concerns should also moti-

This ﬁnding

ASHA.

Examples of tests that fall into this category include

the Frequency Pattern test,55 Gaps-in-Noise (GIN) test,55 and the

Random Gap Detection Test (RGDT).

Tests of Localization and Lateralization

A limited number of measures are available to address localization and lateralization in the clinical setting. The ability to

locate sound eectively in space is a dicult skill to measure and

to move from the laboratory to clinical setting. Masking level

dierence (MLD) has been available for decades, but although

is easy to administer and has been found to be a valid measure of lateralization in children, it is not widely used. Koehnke completed research on a virtual auditory localization test that was easy to use and clinically applicable; however, it has not been adopted for clinical use.59 The Listening in Spatialized Noise—Sentences (LiSN-S) test was developed to address auditory localization in a clinically applicable manner.60 The 3D Listening in Noise Test is one of the components of the Feather Squadron test battery, the newest test materials available for assessing auditory processing in children.

57, 58

Besing and

Monaural Low-Redundancy Tests

Monaural low-redundancy test materials are presented to each ear separately. In these tests, the stimuli have been degraded in a

speciﬁc manner, including altering the frequency characteristics

of the stimuli. Some examples of tests in this category are the

Filtered Words subtest or the Auditory Figure Ground Subtest of

the SCAN-3:C.

Tests of Dichotic Listening

In dichotic listening tests, dierent acoustic stimuli are presented to each ear simultaneously. The listener’s task is to separate the message presented to each ear, also known as binaural separation tasks. These tasks can vary in linguistic load from CV syllable to sentence stimuli. Dichotic listening tasks can provide insight into aspects of hemispheric dominance. This type of test stimuli has been studied for decades as a method of addressing neuromaturation of the auditory system. A right ear advantage (REA), where superior performance for stimuli delivered to the right ear is better than for those delivered to the left ear in dichotic tasks, is considered to be a hallmark of typical auditory development in children; performance is adultlike in typically developing adolescents. Examples of dichotic listening tasks include the Competing Sentences subtest of the SCAN-3:C.

Tests of Binaural Interaction

Tests of binaural interaction require that the listener integrate

dierent auditory information presented between two ears to synthesize the information. The term “ear teaming” could be

used to address how the two ears work together and not in isolation. As just noted, the concept of REA also applies to this group of stimuli. Tests that address this skill set include the Staggered

178

16 Assessment, Treatment, and Management of Auditory Processing Disorders in Children

Spondaic Word test,28 Dichotic CVs,29 and as a subtest in Feather Squadron.

16.3.3 Developing a Test Battery:

Considerations for the Audiologist Performing APD Assessment

Pearl

Administering APD tests to children with typical auditory processing skills is a recommended exercise that provides the audiologist the opportunity to gain experience in understanding typical auditory processing skills and thus have the opportunity

to become procient at test administration and interpretation.

In addition to selecting individual tests, several test batteries

are commercially available. Each is briey described here as an

overview and is not designed to be an exhaustive list of available tools. The importance of a test battery over administration of an individual test has long been established. in test battery development must be considered, including

sensitivity and speciﬁcity, linguistic complexity of stimuli, and

the normative data available. These test batteries have been historically been designed to be administered through a diagnostic audiometer; however, Feather Squadron is administered as an app on an iPad.

The LiSN-S test is used to address the child’s spatial processing abilities. Research from the National Acoustics Laboratories

(NAL) suggests spatial processing disorder (SPD) is a speciﬁc type

of auditory processing disorder resulting in the inability to use directional cues necessary to separate speech from background noise.63 The test simulates a wide variety of listening situations and provides a unique way to examine speech-in-noise performance not available in other test procedures. In addition, a prescribed

gain ampliﬁer (PGA) has been added, which holds promise for

addressing auditory processing skills in children with peripheral hearing loss.

SCAN-3:C or SCAN-3:A61 has subtests including Filtered Words,

Auditory Figure-Ground, Competing Words, Competing Sentences, Time Compressed Sentences, and Gap Detection. The test has both

a screening component and a diagnostic component. The SCAN-

3:C is normed for children between the ages of 5 and 12 years, and

the SCAN-3:A is normed for adolescents and adults between the

ages of 13 and 51 years. The normative data provide opportunities

to compare standard scores with other types of testing, including speech-language and cognitive measures that can contribute to a dierential diagnosis and contribute to understanding educational impact of the APD.

The Multiple Auditory Processing Assessment (MAPA)64 includes

ﬁve dierent subtests and was developed to evaluate auditory

processing disorders in both children and adults, beginning at age

8 years. The MAPA assesses auditory skills in three of the ASHA

domains: monaural low redundancy, auditory pattern temporal ordering, and binaural integration/separation.

A number of factors

Feather Squadron, from Acoustic Pioneer, is the most recent contribution to a test battery assessment. app loaded on an iPad and requires the purchase of special Koss headphones, which are adjusted with the volume control of the iPad, and access to an Internet connection. It purports to address a range of auditory processing skills, and the diagnostic portion of the testing can be administered in 30 minutes. One of the advantages of Feather Squadron is that the results can direct an auditory training program that can also be administered on the iPad.

Auditory Skills Assessment (ASA)65 is a test battery designed to

target 3.5 to 7-year olds, a population that is younger than those

generally assessed with an auditory processing battery. Tasks include speech discrimination in quiet and noise, phonological awareness, nonspeech processing, and mimicry. A premise of

this chapter is that the diagnosis of an APD prior to age 7 is a

challenge because of the variability in auditory behaviors prior to that age and also because of confounding issues of attention, motivation, and language skills of a young child. However, the ASA provides opportunities to practice each task and incorporates picture-pointing tasks to facilitate responses from younger children. Although ASA may not be valid as a tool to identify an APD in

and guide the audiologist over time. Mention of this assessment tool, however, raises the reminder that the audiologist must be

able to address the dicult issue of separating auditory processing delay from an auditory processing disorder. This dierentiation

needs further study, and more tools targeted at tracking auditory development in young children are also needed.

The test battery is an

16.3.4 Electroacoustic Assessment

Tympanometry should always be performed as part of the APD battery to ensure normal middle ear functioning and to rule out the presence of middle ear pathology. Ipsilateral and contralat-

eral acoustic reexes should also be performed to address the integrity of the brainstem pathways and may add to dierential

diagnosis. Otoacoustic emissions (OAEs) should be used to

conﬁrm normal peripheral hearing function. Contralateral suppression of emissions makes it possible to isolate eerent

auditory system function and address the gating function of the auditory system.66 Abnormal contralateral suppression is

thought to be associated with deﬁcits in listening in speech-in-

noise.67 Preliminary studies suggest that children with APD may demonstrate less suppression of transient evoked otoacoustic emission (TEOAE) activity than in an age-matched control group,68 although contradictory ﬁndings are also noted. Clearly, contralateral suppression procedures deserve additional atten-

tion because of the hypothesized relationship between eerent

auditory activity and the ability to listen in the presence of

background noise, since diculty listening in background noise

is one of the most commonly reported behavioral observations in children with suspected APD. Although OAEs may provide a distinctive ability to isolate auditory system function, the contralateral suppression procedure has not been widely adopted

clinically at this time. This is in keeping with the ﬁndings of

Emanuel et al that electroacoustic/electrophysiologic assessment is rarely used in the assessment of APD.

179

II Diagnosing Hearing Disorders in Infants and Children

16.3.5 Electrophysiologic Assessment

As noted in the original ASHA deﬁnition, electrophysiologic

assessment may be considered a critical component of the auditory processing assessment, a sentiment echoed by Jerger and Musiek.69 The beneﬁts of electrophysiologic testing include the ability to use nonspeech stimuli to minimize linguistic load. This eliminates concerns about the behavioral assessment being focused on language measures, makes it possible to minimize attention and motivation as part of the task, and provides a unique measure of auditory system improvement related to treatment/management programs.70 Limitations of electrophysiologic assessment may include the same lack of sensitivity and

speciﬁcity of measures of APD as found in behavioral testing and

the need to speculate between the results of the electrophysiologic measure and functional impact of listening issues in the c

lassroom. In addition, the assumptions inherent in a site-of-

lesion approach may support a disease model but may not apply

to a developmental model. In addition, the cost/beneﬁt ratio for

electrophysiologic assessment may be prohibitive. The AAA clinical practice guidelines suggest that the equipment necessary for

his testing, although readily available in the lab setting, may not

t be available clinically. It is recommended in the AAA guidelines

that the audiologist should deﬁne clinical situations where there

are clear indicators for using auditory evoked response testing, such as when behavioral assessment of APD fails to demonstrate a clear pattern of deﬁcits, when neurologic disorders are anticipated, or when a site-of-lesion assessment is necessary.4 Current research continues to advance use of electrophysiologic testing as a biological marker for APD and to guide intervention strategies.

Several electrophysiologic measures that provide a unique contribution to understanding auditory processing skills can be incorporated into the APD test battery, including auditory brainstem response (ABR) and middle latency response (MLR) assessment.15 As noted by Bamiou and colleagues, ABR and MLR are key measures of the function of auditory structures in the brainstem and in subcortical to cortical levels, respectively.72 Recent research suggests renewed interest in the brainstem and its role in encoding speech information, which supports the importance for this type of electrophysiologic assessment as part of the ABR battery, known as frequency-following response or cABR (ABR to complex

71,73

sound). quency-following response.

Cortical evoked potentials have also been identiﬁed as having

a role in the APD test battery. Electrophysiologic tests provide for assessment of auditory processing skills independent of language skills. The late evoked potentials, such as auditory late response (ALR), mismatched negativity (MMN), and the auditory P300 response can provide documentation of the presence of an APD, either in conjunction with behavioral testing or independent of behavioral results. Increased latencies of ALR responses have been noted in children with APD and have been correlated to slower processing speeds than seen in typically developing age-matched peers. focus in the assessment of auditory processing skills in children.

Signiﬁcant dierence in response parameters (e.g., amplitude,

latency) between children with APD and children with typically developing auditory systems have been noted investigation is needed to address the clinical relevance of these tests in the general pediatric audiology clinical setting.

See Chapter 15 for more information about the fre-

MMN responses and the P300 response have been a

; however, further

Historically, electrophysiologic testing has had a signiﬁcant role

in the identiﬁcation of auditory processing disorders in individu-

als with suspected or known lesions of the CANS. However, when

actice patterns among audiologists performing assessment in

pr children were studied, most reported never using electrophysiologic measures in their test battery.50 However, the landscape for the role of electrophysiologic assessment in the evaluation of APD is clearly changing. As noted previously, incorporating complex stimuli (e.g., speech) into the ABR procedures has proven to be a unique tool for assessing APD skills. Use of complex stimuli for the ABR, such as speech or music, has been found to provide a unique window into how these types of stimulus are processed in the brain.76 This technique has been found to provide a unique snapshot of auditory processing skills at a subcortical level and is useful in both the assessment of auditory processing disorders and in measuring improvement in auditory processing skills, such as after participation in an auditory training program.

The population of children who may need a site-of-lesion assessment has also changed with an increase in concussions in children. Many children who have had concussions report symptoms consistent with an auditory processing disorder, thought to be part of postconcussive syndrome. Equally important, there is currently no one test that can identify a concussion. Frequency-

following response has been identiﬁed as a potential test for identiﬁcation and management of concussion, thus emphasizing

the need for audiology to be involved with this population.

16.4 Management and Treatment

of Auditory Processing Disorders

Developing a comprehensive plan for the treatment and management of APDs is as complex as the process of assessment. One of the fallacies of APD is that nothing can be done to treat it, so assessment is futile. This fallacy is based on the assumption that the only type of treatment or management worth considering results in a cure for the disorder, an approach that is not consistent with how other types of auditory disorders, such as peripheral hearing loss or vestibular disorders, are addressed. Clearly, ﬁtting a hearing aid does not cure a hearing loss; however, the lack of a cure does not negate the positive impact that the hearing aid has on the treatment and management of hearing loss for that child.

Historically, an audiologist would perform an assessment of auditory processing and then provide a preprinted list of recommendations to address general aspects of APD, a strategy to which educators have often retorted that if a list were provided prior to the evaluation, the evaluation would likely be unnecessary. This preprinted list did not support the evidence-based approach to assessment discussed in this chapter and did not address a

deﬁcit-speciﬁc approach to treatment. Several approaches have

been developed to use results of auditory processing to customize a treatment plan to address the individual child’s listening and learning needs. With a greater sophistication in assessment,

development of proﬁles of results and a clearer understanding of neural plasticity lead to a deﬁcit-speciﬁc approach in treatment/ management that is both necessary and possible. The ASHA 2005

statement supports this premise.

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31.08.202641 Мб0Книга_4479_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202641 Мб0Книга_4480_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202640 Мб0Книга_4482_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202640 Мб0Книга_4484_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202639 Мб0Книга_4487_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202638 Мб0Книга_4488_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202638 Мб0Книга_4489_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202636 Мб0Книга_4492_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202636 Мб0Книга_4493_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202636 Мб0Книга_4495_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202636 Мб0Книга_4496_Библиотеки_им_академика_М_И_Перельмана.pdf