Special Education Resources

DIAGNOSIS AND MANAGEMENT OF
CENTRAL AUDITORY PROCESSING DISORDER

Part II: Assessment
Gail D. Chermak, Ph.D.
Washington State University

The brief article below is the second installment of a three part series of brief articles by Dr. Chermak on central auditory processing disorder.

Given the heterogeneous nature of central auditory processing disorder (CAPD) and the range of listening and learning deficits that often coexist with CAPD, comprehensive evaluation requires a multidisciplinary team approach. CAPD is diagnosed by the audiologist on the basis of an extensive audiologic evaluation. Additional evaluation of language development, speech understanding and learning is necessary, however, to identify associated (co-morbid) conditions, as well as clarify the functional impact of CAPD. Speech-language pathologists, psychologists and educators contribute to this more comprehensive assessment. Speech-language and psychoeducational assessment of children with CAPD is beyond the scope of this article. Rather, a minimum test battery for diagnosing CAPD is outlined below.

Behavioral tests are most commonly used to assess the auditory system. Electrophysiological (e.g., auditory brain stem response and middle latency response) and electroacoustic (e.g., immittance measures and otoacoustic emissions) tests are more objective (i.e., less influenced by extraneous factors); however, they 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 CAPD is based on the outcomes of behavioral tests, supplemented by electroacoustic tests, and to a lesser extent supplemented by electrophysiologic measures.

Behavioral assessment begins with a basic audiologic evaluation consisting of pure-tone audiometry, immittance measures, and speech recognition testing. Otoacoustic emissions is a strongly recommended component of the basic evaluation. While the presence of mild-to-moderate peripheral hearing loss confirmed by the basic evaluation does not preclude evaluation of the central auditory system, care must be taken in selecting central tests and in interpreting outcomes in the presence of peripheral hearing impairment.

Evaluation of central auditory processing requires administration of multiple tests spanning the processing categories delineated in the first article of this series. This provides information as to the nature of the CAPD (i.e., which processes are deficient) and guides intervention planning and implementation. The author recommends that a minimum test battery for assessment of central auditory function 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 or words); and 3) monaural low-redundancy speech recognition (e.g., filtered or compressed speech, speech in competition).

The audiologist diagnoses CAPD on the basis of test outcomes. Because these tests employ different tasks to measure different auditory processes, subjects may perform unevenly across tests. The audiologist must determine whether the overall profile confirms CAPD. Diagnosis of CAPD on the basis of one failed test score should only be made if that score is at least 3 standard deviations below the mean performance for the subject's peer group. In such cases, it is helpful to re-test the subject to ascertain the reliability of that measure.

Visit the American Academy of Audiology and the American Speech-Language-Hearing Association web sites for additional information and/or to locate an audiologist or speech-language pathologist in your area.

American Academy of Audiology
8300 Greensboro Dr., Suite 750
McLean, Virginia 22102
Phone: 800-AAA-2336
Fax: 703-790-8631

MEET YOUR PAL

Gail D. Chermak Ph. D., is an Edward R. Meyer Distinguished Professor of Audiology and Chair of the Department of Speech and Hearing Sciences at Washington State University. She earned her doctorate in speech and hearing sciences from the Ohio State University, holds the Certificate of Clinical Competence in Audiology, and is a fellow of the American Academy of Audiology.

Dr. Chermak chaired the ASHA Ad Hoc Committee on Central Auditory Processing which prepared the 1992 report entitled, Issues in Central Auditory Processing Disorders. She served as a member of the ASHA Task Force on Central Auditory Processing Consensus Development responsible for the 1995 report, Central Auditory Processing: Current Status of Research and Implications for Clinical Practice. She was among 14 senior scientists and clinicians who met recently at the University of Texas at Dallas (the Bruton Conference) to reach consensus on best practices in diagnosis of auditory processing problems in school-age children.

Dr. Chermak has published articles and delivered numerous workshops on assessment and management of central auditory processing disorders. Her co-authored articles on central auditory processing disorder and attention deficit hyperactivity disorder have been named by her peers as among the best in diagnostic audiology for the past two consecutive years. Her 1997 book, Central Auditory Processing Disorders: New Perspectives, co-authored with Frank Musiek and published by Singular Publishing Group, has become a landmark volume in the field.