Auditory Temporal Processing as a Specific Deficit among Dyslexic Readers

The present study focuses on examining the hypothesis that auditory temporal perception deficit is a basic cause for reading disabilities among dyslexics. This hypothesis maintains that reading impairment is caused by a fundamental perceptual deficit in processing rapid auditory or visual stimuli. Since the auditory perception involves a number of mechanisms and temporal processing is only one of them, in the current paper, we tested, in addition to auditory temporal processing, also auditory intensity and spectral processing among dyslexic and normal readers. In addition, we examined whether poor performance of dyslexic readers in auditory temporal processing tasks results from a difficulty in working memory, by testing differences in auditory processing, controlling for working memory. Thirty-seven adult dyslexic readers and 40 adult normal readers performed a battery of tests measuring auditory temporal processing (gap detection and dichotic temporal order judgment), auditory intensity processing (absolute threshold and intensity discrimination), auditory spectral processing (spectral temporal order judgment) and working memory (backward digit span). Performance on auditory spectral and temporal processing task was poorer among dyslexic readers, as compared to normal readers, even after controlling for working memory, but no difference was found in intensity processing tasks. These results suggest that dyslexic readers exhibit a specific deficit in auditory temporal processing, which cannot be attributed either to general perceptual deficit in auditory processing, or to working memory. (Contains 2 tables, 3 figures, and 1 footnote.)