Developmental weighting shifts for noise components of fricative-vowel syllables
作者:
Susan Nittrouer,
Marnie E. Miller,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1997)
卷期:
Volume 102,
issue 1
页码: 572-580
ISSN:0001-4966
年代: 1997
DOI:10.1121/1.419730
出版商: Acoustical Society of America
数据来源: AIP
摘要:
Previous studies have convincingly shown that the weight assigned to vocalic formant transitions in decisions of fricative identity for fricative-vowel syllables decreases with development. Although these same studies suggested a developmental increase in the weight assigned to the noise spectrum, the role of the aperiodic-noise portions of the signals in these fricative decisions have not been as well-studied. The purpose of these experiments was to examine more closely developmental shifts in the weight assigned to the aperiodic-noise components of the signals in decisions of syllable-initial fricative identity. Two experiments used noises varying along continua from a clear /s/ percept to a clear /∫/ percept. In experiment 1, these noises were created by combining /s/ and /∫/ noises produced by a human vocal tract at different amplitude ratios, a process that resulted in stimuli differing primarily in the amplitude of a relatively low-frequency (roughly 2.2-kHz) peak. In experiment 2, noises that varied only in the amplitude of a similar low-frequency peak were created with a software synthesizer. Both experiments used synthetic /ɑ/ and /u/ portions, and efforts were made to minimize possible contributions of vocalic formant transitions to fricative labeling. Children and adults labeled the resulting stimuli as /s/ vowel or /∫/ vowel. Combined results of the two experiments showed that children’s responses were less influenced than those of adults by the amplitude of the low-frequency peak of fricative noises.
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