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Objective: Auditory processing disorder (APD) is diagnosed on the basis of listening difficulties despite normal audiogram, although the cause is unknown. This study examined the hypothesis that the underlying cause of APD is a modality-specific deficit in auditory temporal processing and also considered how far the auditory impairments in APD differ from those in children with dyslexia., Design: Performance of children diagnosed with APD (N = 22) was compared with that of a normative group (N = 98) as well as with children with dyslexia (N = 19) on a battery of temporal auditory tasks; 2-Hz frequency modulation (FM), 40-Hz FM, and iterated rippled noise detection as well as a control task (240-Hz FM), which is thought to draw on peripheral spectral mechanisms. Visual tasks were coherent form and coherent motion detection., Results: On average, the APD group performed more poorly than the normative group on the 40-Hz FM, 240-Hz FM, and iterated rippled noise tasks. There were no significant differences between the APD and dyslexia group's performance and no evidence for a specific temporal auditory impairment. A higher proportion of children in the APD group performed poorly (<-1 SD) on the visual tasks than those in the normative group. Auditory psychophysical performance correlated positively with the performance on the SCAN-C, a standardized test of auditory processing, but not with reading ability., Conclusions: The research did not support a modality-specific impairment of temporal auditory processing as being the underlying cause of APD. In both the APD and dyslexia groups, a similar proportion displayed poor auditory performance, and this does not seem entirely accounted for by attention or performance I.Q. However, the significance of these auditory difficulties is uncertain. Serious difficulties with auditory assessment were also identified. Currently, auditory perceptual deficits may be better seen as a part of a multifactorial description of learning problems rather than as part of a diagnostic category in their own right.

Objective: To compare the auditory function of normal-hearing children attending mainstream schools who were referred for an auditory evaluation because of listening/hearing problems (suspected auditory processing disorders [susAPD]) with that of normal-hearing control children., Design: Sixty-five children with a normal standard audiometric evaluation, ages 6-14 yr (32 of whom were referred for susAPD, with the rest age-matched control children), completed a battery of four auditory tests: a dichotic test of competing sentences; a simple discrimination of short tone pairs differing in fundamental frequency at varying interstimulus intervals (TDT); a discrimination task using consonant cluster minimal pairs of real words (CCMP), and an adaptive threshold task for detecting a brief tone presented either simultaneously with a masker (simultaneous masking) or immediately preceding it (backward masking). Regression analyses, including age as a covariate, were performed to determine the extent to which the performance of the two groups differed on each task. Age-corrected z-scores were calculated to evaluate the effectiveness of the complete battery in discriminating the groups., Results: The performance of the susAPD group was significantly poorer than the control group on all but the masking tasks, which failed to differentiate the two groups. The CCMP discriminated the groups most effectively, as it yielded the lowest number of control children with abnormal scores, and performance in both groups was independent of age. By contrast, the proportion of control children who performed poorly on the competing sentences test was unacceptably high. Together, the CCMP (verbal) and TDT (nonverbal) tasks detected impaired listening skills in 56% of the children who were referred to the clinic, compared with 6% of the control children. Performance on the two tasks was not correlated., Conclusions: Two of the four tests evaluated, the CCMP and TDT, proved effective in differentiating the two groups of children of this study. The application of both tests increased the proportion of susAPD children who performed poorly compared with the application of each test alone, while reducing the proportion of control subjects who performed poorly. The findings highlight the importance of carrying out a complete auditory evaluation in children referred for medical attention, even if their standard audiometric evaluation is unremarkable.