Allen P, Nelles J
University of Western Ontario, Department of Communicative Disorders, London, Canada.
J Acoust Soc Am. 1996 Aug;100(2 Pt 1):1043-51. doi: 10.1121/1.416290.
The ability of normal-hearing children (aged 4 through 7 years) and adults to integrate information was measured in an auditory sample discrimination task. On each trial a pair of tonal sequences was played whose component frequencies were randomly drawn from two equal-variance, Gaussian distributions with different means. The listeners task was to identify the sequence drawn from the distribution with the higher mean frequency. Performance was first evaluated as a function of the number of components in each sequence. Results showed that discrimination accuracy improved with increasing age until age 7, at which time performance was adult-like. The 7-year-olds and the adults discriminated the sequences with increasing accuracy as the sequence length was increased, but the 4-to 6-year-old listeners, as a group, did not. Data were fitted with a model with two free parameters, one representing resolution of the components and presumed to reflect peripheral processing, and another representing central noise added to the decision process after the component information is combined [R. Lutfi, J. Acoust. Soc. Am. 86, 934-944 (1989)]. On average, both parameters showed gradual changes as age increased, with adult-like values by 7 years of age. Individual data however suggest that the changes in central noise with age may be less gradual than the changes in peripheral resolution. In a second condition, increases in component duration produced improved performance for the 7-year-olds and the adults, while that of the younger listeners remained the same. Fitted parameters suggested improvements in component resolution for the older children, with no changes in central noise levels. In a third condition, reducing the overlap in the distributions improved performance for only a few of several younger children. This improvement was attributable to lower levels of central noise. Overall, these results suggest that with increasing age children are better able to discriminate between sounds that are variable and have overlapping acoustic characteristics. This age-related improvement may be attributed both to improvements in the ability to resolve the components and to reductions in central noise.
在一项听觉样本辨别任务中，对听力正常的儿童（4至7岁）和成年人整合信息的能力进行了测量。在每次试验中，会播放一对音调序列，其组成频率是从两个均值不同但方差相等的高斯分布中随机抽取的。听众的任务是识别从均值较高的分布中抽取的序列。首先将表现评估为每个序列中成分数量的函数。结果表明，辨别准确率随着年龄增长至7岁而提高，到那时表现已与成年人相似。7岁儿童和成年人随着序列长度增加，辨别序列的准确率也在提高，但4至6岁的听众作为一个群体则不然。数据用一个具有两个自由参数的模型进行拟合，一个参数代表成分的分辨率，假定反映外周处理，另一个参数代表在成分信息组合后添加到决策过程中的中枢噪声[R. 卢特菲，《美国声学学会杂志》86, 934 - 944(1989)]。平均而言，随着年龄增长，两个参数都显示出逐渐变化，到7岁时达到类似成年人的值。然而，个体数据表明，中枢噪声随年龄的变化可能不如外周分辨率的变化那么平缓。在第二种情况下，成分持续时间的增加使7岁儿童和成年人的表现有所改善，而年幼听众的表现保持不变。拟合参数表明年龄较大儿童的成分分辨率有所提高，中枢噪声水平没有变化。在第三种情况下，减少分布的重叠仅使几个年幼儿童中的少数表现有所改善。这种改善归因于较低水平的中枢噪声。总体而言，这些结果表明，随着年龄增长，儿童能够更好地辨别可变且具有重叠声学特征的声音。这种与年龄相关的改善可能既归因于分辨成分能力的提高，也归因于中枢噪声的降低。
