Kerry M.M. Walker
David K. Brown
Dennis P. Phillips
Several studies have suggested that auditory processing Disorders (APD), as defined by standard clinical testing, can be associated with or contribute to the development of generalized learning disabilities (Pinheiro, 1977; Willeford, 1977), as well as more specific reading, language, and attention deficit disorders (Cacace & McFarland, 1998). However, it is unclear whether the type of auditory processing disorder that leads to a positive APD diagnosis is equivalent to the auditory temporal processes that have been shown to relate to reading and language performance. Furthermore, studies of APD usually only test sensory processing in the auditory domain, so the existence of a multi modal processing disorder is not ruled out.
A major finding of the present study was that the participants with LI were also found to be impaired on several of our temporal processing tasks.
…. the second major finding of the present study. If auditory temporal processing development plays an important role in language and reading proficiency, then one might expect these two measures to be correlated within individuals. Across all subjects in our study, we found a correlation of phonological awareness and reading performance with tasks of relative timing judgments, particularly in the auditory domain. The correlation between reading and temporal order judgements persisted within our group of control subjects.
Finally, it is possible that language impairment and APD on the one hand, and performance on temporal processing tasks on the other,are all influenced by a third variable. The most obvious candidate for such a third variable correlation is general cognition. However, it has been shown empirically that attentional and other cognitive factors play only a minor role in the tasks required for diagnosis of APD or dyslexia (Illadou et al., 2009; Sharma et al., 2009; Cohen-Mimran and Sapier, 2009; Dawes et al., 2009). Tallal and Piercy (1973) demonstrated differential performance on an auditory temporal ordering task (“repetition test”) in IQ-matched normal and language-learning impaired children. This task was very similar to our own sequential temporal order judgement task. These data do not support a view that temporal processing performance and reading performance are each mediated by a third (cognitive) factor.
The present study provides further evidence for relative timing deficits in a clinical group with impoverished reading and phonological awareness performance. The results suggest that an APD may impact reading, phonological awareness and relative timing judgments in individuals with LI. Based on our data alone, it remains impossible to tell whether a deficit in temporal processing judgments may lead to impaired language and reading performance, or vice versa.