Auditory processing disorder (APD), also known as central auditory processing disorder (CAPD) refers to difficulty using auditory information for communication and learning.Simply speaking, auditory processing refers to how the brain uses what the ears are hearing. In most cases, children with APD have normal hearing, although fluctuating hearing loss related to ear infections during infancy and early childhood is often present in the history. Auditory processes that are deficient in individuals with APD include:
- Phonemic Decoding (recognizing the sounds of speech quickly and accurately)
- Dichotic listening (processing competing messages)
- Binaural integration (the ability of both ears to work together efficiently)
- Auditory closure (filling in information that is missing due to distortion, etc.)
- Temporal patterning (recognizing acoustic contours and sequencing auditory stimuli)
The incidence of APD has been estimated by Chermak and Musiek (1998) at three to five percent, higher than the incidence of hearing loss.
Symptoms of APD
Behavioral manifestations of APD include distractibility,'selective' hearing, hypersensitivity to loud sounds, preference for visual activities, difficulty following multi-step directions, taking notes and completing assignments, delays in responding and need for repetition, better performance in one-on-one situations and reading/spelling/writing problems,often related to deficits in phonemic awareness. Because of the tendency of APD to coexist with other conditions, children with the problems described above may also have attention deficits (ADD or ADHD), speech and language impair mentand/or learning disability (LD).
Determining Candidacy for Testing
Children with severe speech/language or cognitive delays are not considered to be candidates for testing because of the probability that these problems will prevent an accurate assessment of AP abilities. In this population, APD, if present, will be most likely be secondary to more global deficits affecting communication and learning, often already being addressed in school. Hearing impaired individuals are assumed to have auditory processing deficits due to faulty acoustic input, and are not candidates for AP testing. In addition, testing is not performed prior to age 7 due to neuromaturational factors.
Auditory Processing Tests
The auditory processing test battery consists of behavioral tests designed to measure processes such as phonemic decoding, dichotic listening, binaural integration, auditory closure and temporal patterning. For older children, electrophysiological tests such as middle latency response (MLR) may be used to contribute to the diagnosis.
Interpreting the Results
Once APD has been identified and categorized, the individual's communication/learning problems are analyzed in relation to the deficit and specific recommendations are made. In order to accomplish this goal and assess the effects of other deficits on auditory processing, speech/language and psycho-educational testing is required prior to the AP evaluation.
Management of APD
Management of APD encompasses three areas: remediation, compensatory strategies and environmental modifications. Remediation seeks to improve auditory processing skills and may include efforts to improve phonemic awareness, auditory closure, dichotic listening, etc. This therapy is generally conducted by a speech-language pathologist, and computerized programs(e.g., Earobics) are also available for use at home. Compensatory strategies are aimed at strengthening 'top-down' linguistic and cognitive skills to help compensate for 'bottom-up' auditory perceptual deficits. Environmental modifications consist of strategies to improve the acoustic environment and facilitate optimal classroom and academic performance. Some of these strategies (e.g., simplification and repetition of instructions, cuing and comprehension checks, use of visual cues and written material to supplement auditory information, extended time for testing and individualized instruction) are also recommended for children with attention and learning problems. Many of these children also need remedial reading help, including work on phonological coding to improve their word attack skills. For children under age 7 who cannot be formally tested, phonemic awareness training and environmental modifications are recommended, as needed.
APD is a complicated problem that is best handled with a team approach. Audiologists, speech-language pathologists, neurologists, psychologists and educators may all be involved in identifying the disorder and differentiating it from other deficits such as language impairment, ADHD and LD. These same professionals, in alliance with parents, should then become involved in recommending and implementing management strategies. In this way, the child can be helped to cope with his deficits and reach his potential for successful communication and learning.