Effects of lengthened formant transition duration on discrimination and neural representation of synthetic CV syllables by normal and learning-disabled children
Effects of lengthened formant transition duration on discrimination and neural representation of synthetic CV syllables by normal and learning-disabled children
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DOI：
10.1121/1.427953
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发表时间：
1999-10-01
影响因子：
2.4
通讯作者：
Zecker, SG
中科院分区：
文献类型：
--
作者：
Bradlow, AR;Kraus, N;Zecker, SG
为了研究学习困难儿童塞音的声学特征，比较了学习困难儿童和正常儿童沿沿着两个合成音/da-ga音/连续音的辨别阈值。连续谱的不同之处仅在于共振峰转换的持续时间。结果表明，简单地延长共振峰转换持续时间从40至80毫秒并没有导致改善的识别阈值的LP组相对于正常组。与先前的发现一致，Bn电生理反应反映了大脑对从一种听觉刺激到另一种听觉刺激的变化的表征--失配负波（MMN）--表明LP组相对于正常组对/da/和/ga/的反应减弱。在延长的过渡期条件下，LP组的MMN反应与与正常组相比，短过渡期条件下增强。这些数据表明，延长声学刺激的关键部分的持续时间可以导致在预注意神经水平增强编码;然而，这种刺激操纵本身并不足以增强声学增强，以促进这种发音对比度的感知辨别。(C)1999年美国声学学会。[S0001-4966（99）00210-6]。
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, Bn 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. (C) 1999 Acoustical Society of America. [S0001-4966(99)00210-6].