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In order to investigate the precise acoustic features of stop consonants that pose perceptual difficulties for some children with learning problems, discrimination thresholds along two separate synthetic /da-ga/ continua were compared in a group of children with learning problems (LP) and a group of normal children. The continua differed only in the duration of the formant transitions. Results showed that simply lengthening the formant transition duration from 40 to 80 ms did not result in improved discrimination thresholds for the LP group relative to the normal group. Consistent with previous findings, an electrophysiologic response that is known to reflect the brain's representation of a change from one auditory stimulus to another--the mismatch negativity (MMN)--indicated diminished responses in the LP group relative to the normal group to /da/ versus /ga/ when the transition duration was 40 ms. In the lengthened transition duration condition the MMN responses from the LP group were more similar to those from the normal group, and were enhanced relative to the short transition duration condition. These data suggest that extending the duration of the critical portion of the acoustic stimulus can result in enhanced encoding at a preattentive neural level; however, this stimulus manipulation on its own is not a sufficient acoustic enhancement to facilitate increased perceptual discrimination of this place-of-articulation contrast.

Language‐based learning problems affect approximately one person in twelve with no other obvious signs of disorder. Many of these individuals have accompanying deficits in nonlinguistic perception. To determine whether age influences the magnitude of these deficits, thresholds on a set of auditory masking tasks were measured in individuals with learning problems and controls ranging in age from 6 years to adult. Performance improved with increasing age in both groups. However, the thresholds of the individuals with learning problems were most similar to those of controls approximately 2–4 years younger on every task, suggesting that the perceptual development of the affected individuals was delayed by a constant amount. Further, on the subset of conditions on which controls reached adult levels of performance after 10 years of age, the improvement of affected individuals halted at 10 years of age, suggesting that puberty may play a critical role in human perceptual development. Taken together, these data ...

This work concerns the relationship between two measures of auditory processing and several measures of cognitive abilities. The discriminabilities of formant transitions in synthesized consonant–vowel syllables were collected from over 100 children aged 7–11. Specifically, the discriminabilities of the F3 onset frequencies were measured in a set of stimuli which ranged perceptually from /dopen aye/ from /gopen aye/. Also, the discriminabilities of the onset transition durations of F1, F2, and F3 were measured in stimuli which ranged perceptually from /bopen aye/ to /wopen aye/. A PEST adaptive tracking paradigm was employed to make these measurements. The average just noticeable difference was 101 Hz for the F3 onset frequencies and 6 ms for the F1, F2, and F3 frequency ramps. A battery of tests of cognitive ability were administered to the same children. The cognitive ability tests revealed a wide range of scores in the subjects tested. A correlational analysis of these data indicated that better onset ...