This result was confirmed by the findings of Heiervang et al. However, when the same stimuli were applied at reduced intervals (305 to 8 ms), children with dyslexia presented a higher number of incorrect answers, not only for the sequencing test, but also for the discrimination test. According to Tallal (12), one of the pioneers of this hypothesis, one of the reasons for the existence of such doubts is related to the characteristics of the stimuli and to the tasks considered for the tests used.įor example, in the auditory processing tests employed (Repetition Test) in a study conducted by Tallal (1), children with dyslexia displayed the same level of performance as control children when the interstimulus intervals (ISIs) were long (428 ms). Consequently, they would be unable to associate letters with their specific sounds (1-5).ĭespite the large number of studies associating dyslexia with auditory temporal processing (1,5-7), there still is some controversy about this association (8-11). Thus, dyslexic individuals appear to have difficulties in perceiving and distinguishing these sounds properly within the speech spectrum. More specifically, this auditory temporal processing difficulty can be described as the limited ability to process "acoustic elements of short duration" - such as consonants with rapid formant transitions. One of the hypotheses under study is based on auditory temporal processing deficiency. Several theories have been developed in order to discover the etiology of dyslexia, a reading problem. Key words: Auditory temporal processing Dyslexia Hearing tests Children Introduction How auditory temporal processing deficits relate to dyslexiaĭepartamento de Fisioterapia, Fonoaudiologia e Terapia Ocupacional, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil These results support the hypothesis that associates dyslexia with auditory temporal processing, identifying the stimulus-duration variable as the only one that unequally influenced the performance of the two groups.Īuditory temporal processing Dyslexia Hearing tests Childrenīraz J Med Biol Res, July 2009, Volume 42(7) 647-654 Moreover, there was an interactive effect between the group and the duration of stimulus variables for the frequency-pattern tests, with the dyslexic group demonstrating significantly lower results for short durations (53.4 ± 8.2 vs 48.4 ± 11.1), as opposed to no difference in performance for the control group (62.2 ± 7.1 vs 60.6 ± 7.9). Results showed a significant difference in the average accuracy of control and dyslexic groups considering each variable (interstimulus intervals: 47.9 ± 5.5 vs 37.18 ± 6.0 stimulus duration: 61.4 ± 7.6 vs 50.9 ± 9.0 type of task: 59.9 ± 7.9 vs 46.5 ± 9.0) and the dyslexic group demonstrated significantly lower performance in all situations. Auditory processing tests assess the abilities of discrimination and ordering of stimuli in relation to their duration and frequency. Of the 60 children evaluated, 33 were dyslexic (mean age = 10.5 years) and 27 were normal controls (mean age = 10.8 years). Therefore, the purpose of the present study was to analyze by auditory temporal processing tests the effect of temporal variables such as interstimulus intervals, stimulus duration and type of task on dyslexic children compared to a control group. However, discussion continues concerning the way this deficiency can be influenced by temporal variables of auditory processing tests. Studies have shown that dyslexic children present a deficiency in the temporal processing of auditory stimuli applied in rapid succession.
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