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Children who have difficulty using information they hear in academic and social situations may have central auditory processing disorder (CAPD), more recently termed auditory processing disorder (APD). These children typically can hear information but have difficulty attending to, storing, locating, retrieving, and/or clarifying that information to make it useful for academic and social purposes (Katz & Wilde, 1994). This can have a negative impact on both language acquisition and academic performance. WHAT IS CENTRAL AUDITORY PROCESSING? When the ears detect sound, the auditory stimulus travels through the structures of the ears, or the peripheral auditory system, to the central auditory nervous system that extends from the brain stem to the temporal lobes of the cerebral cortex. The auditory stimulus travels along the neural pathways where it is "processed," allowing the listener to determine the direction from which the sound comes, identify the type of sound, separate the sound from background noise, and interpret the sound. The listener builds upon what is heard by storing, retrieving, or clarifying the auditory information to make it functionally useful. WHAT IS A DISORDER OF AUDITORY PROCESSING? APD is an impaired ability to attend to, discriminate, remember, recognize, or comprehend information presented auditorily in individuals who typically exhibit normal intelligence and normal hearing (Keith, 1995). This definition has been expanded to include the effects that peripheral hearing loss may contribute to auditory processing deficits (Jerger & Musiek, 2000). Auditory processing difficulties become more pronounced in challenging listening situations, such as noisy backgrounds or poor acoustic environments, great distances from the speaker, speakers with fast speaking rates, or speakers with foreign accents (Sloan, 1998). WHAT ARE THE BEHAVIORS OF CHILDREN WITH APD? Children who have auditory processing disorders may behave as if they have a hearing loss. While not all children present all behaviors, Keith (1995) offers the following examples of behaviors that may be displayed by children who have APD: - Inconsistent response to speech
- Frequent requests for repetition (What? Huh?)
- Difficulty listening or paying attention in noisy environments
- Often misunderstanding what is said
- Difficulty following long directions
- Poor memory for information presented verbally
- Difficulty discerning direction from which sound is coming
- History of middle ear infection.
WHAT ARE ACADEMIC CHARACTERISTICS OF CHILDREN WHO HAVE APD? In addition to the preceding behaviors, children may also present a variety of academic characteristics that may lead teachers and parents to suspect APD. Baran (1998) offers the following characteristics. Again, all children will not present all characteristics. - Poor expressive and receptive language abilities
- Poor reading, writing, and spelling
- Poor phonics and speech sound discrimination
- Difficulty taking notes
- Difficulty learning foreign languages
- Weak short-term memory
- Behavioral, psychological, and/or social problems resulting from poor language and academic skills.
HOW IS APD DIAGNOSED? Given the complexity of auditory processing disorders, it is important to involve a multidisciplinary team including psychologists, physicians, teachers, parents, and of course, audiologists and speech-language pathologists. Audiologists diagnose the presence of APD (hearing and processing problems), and speech-language pathologists evaluate a child's perception of speech and receptive- expressive language use. Other team members conduct additional assessments to determine a child's educational strengths and weaknesses. Checklists that ask teachers and parents to observe the child's auditory behaviors may be used to determine a need for the APD evaluation. The parent's description of the child's auditory behavior at home is an especially important contribution to the diagnosis of APD. WHAT DOES THE AUDIOLOGIST DO? The audiologist assesses the peripheral and central auditory systems using a battery of tests, which may include both electrophysiological and behavioral tests. Peripheral hearing tests determine if the child has a hearing loss and, if so, the degree to which the loss is a factor in the child's learning problems. Assessment of the central auditory system evaluates the child's ability to respond under different conditions of auditory signal distortion and competition. It is based on the assumption that a child with an intact auditory system can tolerate mild distortions of speech and still understand it, while a child with APD will encounter difficulty when the auditory system is stressed by signal distortion and competing messages (Keith, 1995). The test results allow the audiologist to identify strengths and weaknesses in the child's auditory system that can be used to develop educational and remedial intervention strategies. HOW SHOULD TEST RESULTS BE INTERPRETED? As with any kind of evaluation, test results should be interpreted with caution. The effects of neurological maturation may influence test results for children under the age of 12 years. A true diagnosis of APD cannot be determined until that time (Bellis, 1996). However, there are much younger children whose auditory behaviors, language, and academic characteristics indicate that APD is a strong possibility, and even without a formal diagnosis, these children would benefit from intervention. Remediation should address their strengths and areas of need based on available speech-language and psychoeducational testing.
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