It has been proposed that specific language impairment (SLI) is caused by an impairment of auditory processing, but it is unclear whether this problem affects temporal processing, frequency discrimination (FD), or both. Furthermore, there are few longitudinal studies in this area, making it hard to establish whether any deficit represents a developmental lag or a more permanent deficit. To address these issues, the authors retested a group of 10 children with SLI and 12 control children first tested 42 months previously. At Time 1, the children with SLI (between 9 and 12 years of age) had significantly elevated FD thresholds compared to the matched controls. At Time 2, the thresholds of both groups had improved, but the children with SLI still had poorer FD thresholds than those of the controls. To assess temporal resolution, auditory backward masking was measured and it was found that most of the children with SLI performed as well as the controls, but 2 children had exceptionally high thresholds. There was also greater variability among the children with SLI compared to that measured among the controls on the FD task. These studies indicate considerable heterogeneity in auditory function among children with SLI and suggest that, as with auditory temporal deficits, difficulties in FD discrimination are important in this population.

Children have higher auditory backward masking (BM) thresholds than adults. One explanation for this is poor temporal resolution, resulting in difficulty separating brief or rapidly presented sounds. This implies that the auditory temporal window is broader in children than in adults. Alternatively, elevated BM thresholds in children may indicate poor processing efficiency. In this case, children would need a higher signal-to-masker ratio than adults to detect the presence of a signal. This would result in poor performance on a number of psychoacoustic tasks but would be particularly marked in BM due to the compressive nonlinearity of the basilar membrane. The objective of the present study was to examine the competing hypotheses of "temporal resolution" and "efficiency" by measuring BM as a function of signal-to-masker interval in children and adults. The children had significantly higher thresholds than the adults at each of the intervals. Subsequent modeling and analyses showed that the data for both children and adults were best fitted using the same, fixed temporal window. Therefore, the differences in BM threshold between adults and children were not due to differences in temporal resolution but to reduced detection efficiency in the children.

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There is electrophysiological evidence that phonological categorization has occurred within 100-200 ms post stimulus onset for the syllables /tae/ and /dae/, which vary in voice onset time. Using a similar paradigm, this study investigated when phonological categorization occurred for the contrast between /I/ and /epsilon/, using synthesized speech tokens that differed in the frequency of the first formant. Here we show that phonological categorization of these tokens has not occurred 100-200 ms after stimulus onset. However, the presence of a late mismatch negativity (350 ms after stimulus onset) indicated that phonological categorization had taken place by this time.

SUMMARY Secretory otitis media is a very common disorder in early childhood, but its effects on language development are still uncertain. We describe 10 children with secretory otitis media and illustrate the wide range of disability attributable to this. It There has been much concern over the possible effects of middle ear disease on learning in general and language development in particular. This relation has been examined in over 30 published reports, and in most, significant correlations have been shown.6 The majority of these studies, however, contain serious flaws in design. Most are retrospective, and therefore the precise diagnosis is often uncertain in the children with a history of ear disease; conversely the absence of previous ear disease in the control group cannot be shown. For the same reason, the number and duration of attacks, the severity of the hearing loss, and the distinction between unilateral and bilateral disease are seldom documented. Lastly, matching of cases and controls for psychosocial variables is seldom adequate, yet accurate matching is essential since the prevalence and perhaps the management of secretory otitis media are related to race, size of household, and social status, and these variables also influence development. It must therefore be said that the case for a cause and effect relation between secretory otitis media and learning problems remains unproved.7Despite shortcomings of published research, most clinicians with an interest in this field are convinced that secretory otitis media is indeed an important cause of developmental problems in young children. The purpose of this paper is to present some illustrative case histories; to derive from these a working hypothesis on the nature of the relation between secretory otitis media and developmental problems; and to discuss the type of research design needed to investigate this hypothesis. Methods and case reportsThe children described here were seen in two children's audiology clinics over a three year period.