Teri James Bellis, Ph.D.
Department of Communication Disorders
University of South Dakota
Barbara Roe Beck, M.A.
Department of Communication Sciences and Disorders
Saint Louis University
St. Louis, MO
Clinical delivery of central auditory assessment and management services has become a much-debated topic in recent years partly due to explosive increases in referrals for such services. Requests for information regarding central auditory processing disorders (CAPD) commonly come from educators, pediatricians, speech-language pathologists, parents, educational psychologists and neurologists. The purpose of this article is to address some of the key issues the authors believe impact the delivery of central auditory services in a clinical setting.
CAPD has been defined as a deficit in one or more of the auditory mechanisms which underlie tasks such as localization and lateralization, discrimination, temporal processing and performance under conditions of degraded and/or competing acoustic signals. Furthermore, CAPD may occur alone or may coexist with higher-level, global disorders which impact general processing abilities, including attention- and language-related disorders (ASHA, 1996).
CAPD may occur in children and adults. In our experience, the majority of pediatric referrals are initiated by the child's school district (which then accepts responsibility for paying for the evaluation) or by the parent(s). In these situations, CAPD frequently is suspected prior to the referral. Conversely, the majority of adults arrive at the clinic for audiologic evaluation because of auditory difficulties that may be indicative of peripheral hearing loss. The topic of possible CAPD arises only after it is determined that the degree of auditory difficulty exhibited by the individual cannot be accounted for by the degree of peripheral auditory dysfunction, if any.
There are a number of common symptoms which may trigger a referral for a central auditory evaluation in a child or an adult (see Bellis, 1996 and Bellis & Ferre, 1999 for reviews). The most pervasive complaint is difficulty understanding speech in noisy or reverberant environments which cannot be accounted for by peripheral auditory dysfunction (Olson, Noffsinger, & Kurdziel, 1975).
Children with CAPD often exhibit a wide variety of academic and communicative complaints, including inability to follow complex verbal directions; poor verbal cognitive performance as compared to nonverbal performance; spelling and reading difficulties; receptive language delay or disorder; unwillingness to engage in classroom discussion or, alternatively, inappropriate or off-topic contributions to conversational exchanges; poor sound blending, discrimination, and segmentation skills and difficulty maintaining attention to information presented auditorily. These same children frequently request many repetitions, may be easily distracted and may exhibit signs of frustration, especially in language-based courses such as social sciences.
As such, it is important that children exhibiting academic or communicative difficulty be evaluated with respect to overall cognitive function, receptive and expressive language skills, and attention and psychoeducational/academic functioning. This serves to assist in the differential diagnosis of CAPD and to determine the relative contribution of a CAPD to the child's overall difficulties (Bellis & Ferre, 1999). For school-aged children exhibiting academic difficulties, such assessments frequently are completed as part of the special education evaluation within the school setting. The information obtained from such assessments is valuable to the audiologist engaged in assessing CAPD. Therefore, the authors recommend such assessments be completed prior to referral for central auditory processing assessment.
These non-auditory assessments help determine the child's levels of functioning for cognitive, language and academic domains which may impact the child's ability to process incoming information. It will also serve to determine the need for central auditory assessment. In short, the audiologist engaged in central auditory assessment of school-age children, whether in the educational or clinical setting, should be viewed as an integral part of the multidisciplinary special education team. Decisions regarding assessment and management should be undertaken from a team perspective. This requires close collaboration between the audiologist and the educational team members throughout the evaluation and management process.
Once the need for central auditory assessment has been determined, the audiologist chooses the CAPD tools utilized. Tests of CAPD must yield information which contributes to the specific management of each case.
Too often, children are referred for CAPD assessment, only to leave with the 'same old' lists of environmental modifications and studying strategies. These lists, while offering suggestions beneficial to all children (and especially those with CAPD), are often the 'least common denominators' of remedial techniques.
Rather, tests should address the processes that contribute to the symptoms the child or adult experiences. Remediation/rehabilitation can then target areas of specific weakness. The authors believe a 'test battery' approach using tools proven to be sensitive to known dysfunctions of the central auditory pathways is the most effective method of assessing central auditory function. Tests included in the battery should provide information about various central auditory processes. Additionally, when testing children, the battery as a whole must not exceed the child's ability to attend, to ensure the results reflect optimal performance.
Given the parameters listed, the authors employ a battery that includes tests of dichotic listening, monaural low-redundancy speech, temporal patterning and binaural interaction. Examples of specific tools used within the test battery include, but are not limited to, the Staggered Spondaic Word test (SSW; Katz, 1962); Dichotic Digits (Musiek, 1983), Competing Sentences Test (e.g., Willeford & Burleigh, 1994), Duration Patterns Test (Pinheiro & Musiek, 1985), Pitch Pattern Sequence (or Frequency Patterns) Test (Pinheiro & Ptacek, 1971; Ptacek & Pinheiro, 1971), speech in the presence of ipsilateral and/or contralateral speech noise, low-pass filtered speech, time-compressed speech with and without reverberation, masking level difference, and binaural fusion tests. In some cases, electrophysiologic measures designed to assess the integrity of the auditory brainstem, thalamus, and cortex may be employed, including the auditory brainstem response (ABR), middle latency response (MLR), late evoked responses (LER; including N1-P2 and the P300), and the mismatch negativity response (MMN). Using a 'core battery' is not uncommon, with selection of additional specific tests depending on the nature of the child's difficulties and the results of previous audiologic and non-audiologic evaluations.
As previously stated, once the processes (not symptoms) that underlie the areas of weakness are identified, remediation can be targeted to meet the specific needs of each individual. Care must be taken to address various communicative environments in which the person is regularly involved. For example, a large part of a child's time is spent in school, but what about the home environment? How many family members live there? Are bedrooms shared? Does the family eat meals together regularly? What about social groups: Boy or Girl Scouts, team sports, religious groups?
If the CAPD patient is an adult, it is important to consider what his or her work environment is like. Is communication generally one-on-one or in small groups, are large group discussions common? How noisy is the work environment? In essence, the audiologist must assess the communication needs of the patient in their work, home and social environments.
'Learning' takes place in a variety of contexts. Patients with CAPD need training in compensatory strategies so they may be successful in each context. This can be accomplished only by utilizing the expertise of the family members and other professionals involved in the person's care. Audiologists who work with persons exhibiting CAPD should be prepared to learn from other professionals how a person's physical, emotional, intellectual and psychological attributes contribute to his or her communication abilities. Conversely, we should be prepared to teach family members and colleagues how to maximize the individual's potential for successful auditory learning. Audiologists should use their counseling and rehabilitative skills with patients demonstrating CAP -- despite normal peripheral hearing.
Finally, remediation activities designed to address specific dysfunctional processes need to be included in the management plan. Such activities should be deficit-specific in nature, challenging to the individual and should be undertaken in a manner which maximizes generalization across a variety of communicative and learning situations. Remediation techniques may include activities such as phonological awareness and discrimination training (including speech-to-print skills), auditory closure activities, prosody training (including rhythm and stress perception), speechreading, and exercises to improve interhemispheric transfer of information.
In brief, management for CAPD should encompass three primary areas: ensuring that the learning and/or communicative environment is acoustically accessible to the individual at home and in the workplace (or school), assisting the individual with strategies to compensate for his or her own auditory difficulties and therapeutic activities designed to remediate the specific processes which contribute to the disorder.
A common question regarding CAPD management is: Who shoulders the primary burden of overseeing and implementing the intervention program? Again, it should be emphasized that management of CAPD is a multidisciplinary team effort. Thus, the most appropriate person(s) to implement various aspects of the program is dictated most often by the nature of the intervention. For example, teaching-based classroom modifications to aid a child in the learning environment will be the responsibility of the classroom teacher, whereas improving classroom acoustics and provision of assistive listening devices typically will fall under the direction of the audiologist. Provision of direct therapy services may be undertaken by any of a number of professionals. For instance, language and phonological-related goals frequently may be addressed by the speech-language pathologist. On the other hand, if phonological awareness and speech-to-print activities to assist spelling and reading are of primary importance, phoneme training activities may be integrated into the services provided by the reading specialist or resource teacher. In some settings, the audiologist is the primary service provider for aural rehabilitation services, including those related to CAPD. Exercises that focus on interhemispheric transfer of information typically include cross-modality activities. Therefore, these exercises are sometimes overseen by the occupational or physical therapist. Finally, with the advent of the home computer, many activities appropriate for CAPD remediation may be carried out on an at-home basis and supervised by the child's parent or the individual with CAPD him- or herself, with occasional professional guidance.
A final topic of concern is that of who shoulders the financial burden for central auditory assessment and management. In our practices, these services most commonly are paid for by the school district if the assessment results from a direct referral from the district. In other cases, the parent(s) or individual client is responsible for payment for services. The issue of third party reimbursement for central auditory assessment remains unresolved. Some insurance companies exhibit a relatively high reimbursement rate on a case-by-case basis, and others deny payment completely.
In our experience, it has been useful to code and bill for the assessment as a whole, using a generalized speech-language or central auditory assessment CPT code (i.e., 92506 or 92589), rather than billing for each test separately. Electrophysiologic assessment services typically are considered as separate billing issues (i.e., 92585 for auditory brainstem response testing). Lastly, it is suggested that pre-authorization be obtained from the insurance company (when applicable) prior to assessment, so all parties are informed as to the distribution of financial responsibilities.
In conclusion, clinicians involved in the assessment and management of CAPD must take many factors into account. Chief among these are the determination of who is an appropriate candidate for services, what measures to include in the test battery, which management approaches are indicated, who should oversee intervention and management and who will be financially responsible for the services.
It is our opinion that any assessment of CAPD should involve a test battery approach using measures previously shown to be sensitive to central auditory dysfunction. Furthermore, any central auditory assessment ultimately should result in management suggestions directed toward the specific dysfunctional processes and areas of learning and communicative difficulty exhibited by the individual child or adult.
The provision of central auditory services requires both a significant time commitment on the part of the clinician as well as a repertoire of knowledge and skills which often extend beyond traditional clinical audiologic training.
Finally, any provider of central auditory services should be part of a larger, multidisciplinary team dedicated to addressing the overall learning and/or communicative difficulties of the individual. Only then, can central auditory services in a clinical practice be considered to be comprehensive in nature.
American Speech-Language-Hearing Association Task Force on Central Auditory Processing Consensus Development (1996). Central auditory processing: current status of research and implications for clinical practice. American Journal of Audiology, 5, 41-54.
Bellis, T.J. (1996). Assessment and management of central auditory processing disorders in the educational setting: from science to practice. San Diego, CA: Singular Publishing Group.
Bellis, T.J., & Ferre, J.M. (1999). Multidisciplinary approach to the differential diagnosis of central auditory processing disorders in children. Journal of the American Academy of Audiology, 10, 319-328.
Katz, J. (1962). The use of staggered spondaic words for assessing the integrity of the central auditory nervous system. Journal of Auditory Research, 2, 327-337.
Musiek, F. E. (1983). Assessment of central auditory dysfunction: The Dichotic Digits Test revisited. Ear and Hearing, 4, 79-83.
Olson, W.O., Noffsinger, D., & Kurdziel, S. (1975). Speech discrimination in quiet and in white noise by patients with peripheral and central lesions. Acta Otoloaryngologica, 80, 375-382.
Pinheiro, M. L., & Musiek, F. E. (1985). Sequencing and temporal ordering in the auditory system. In M. L. Pinheiro & F. E. Musiek (Eds.), Assessment of central auditory dysfunction: foundations and clinical correlates (pp. 219-238). Baltimore, MD: Williams & Wilkins.
Pinheiro, M. L., & Ptacek, P. H. (1971). Reversals in the perception of noise and tone patterns. Journal of the Acoustical Society of America, 49, 1778-1782.
Ptacek, P. H., & Pinheiro, M. L. (1971). Pattern reversal in auditory perception. Journal of the Acoustical Society of America, 49, 493-498.
Willeford, J.A., & Burleigh, J. M. (1994). Sentence procedures in central testing. In J. Katz (Ed.), Handbook of clinical audiology, fourth edition (pp. 256-268). Baltimore, MD: Williams & Wilkins.