Central auditory processing development in adolescents with and without learning disabilities

Auditory processing deficit (APD) is estimated to affect 5% of school-age children and adolescents, and 30-50% of those diagnosed with learning problems. The diagnosis and indeed the existence of APD, however, remain controversial. One reason for this controversy is that the factors contributing to normal variations in auditory processing and its development are poorly understood. To address the developmental issue, we compared the performance of younger (14 yr/o) and older (18 yr/o) adolescents on frequency discrimination, backward masking detection and gap detection using an oddball paradigm. Older adolescents had lower backward masking thresholds compared with younger adolescents, but the prolonged development of thresholds was not accompanied by a corresponding increase in performance consistency. The distribution of thresholds on all three tasks did not differ between typically developing adolescents and those diagnosed with learning disabilities. A questionnaire designed to tap difficulties in daily listening situations also failed to differentiate the two groups. These findings suggest that basing the diagnosis of APD on tests conducted with the oddball procedure requires the establishment of norms from large and age specific samples. They also suggest that the development of auditory sensory acuity in the general population is longer than typically assumed.