Miller J L, Baer T
J Acoust Soc Am. 1983 May;73(5):1751-5. doi: 10.1121/1.389399.
One of the acoustic properties distinguishing the syllable-initial stop consonant /b/ from the semivowel /w/ is the duration of the initial formant transitions; syllables beginning with /b/ have shorter transitions than those beginning with /w/. This experiment investigated the way in which the transition durations of /b/ and /w/ change as a function of speaking rate by examining tokens of /ba/ and /wa/ produced by four male speakers. At any given speaking rate the /wa/ transitions were, on average, longer than the /ba/ transitions, although pooled across rates, the distributions of transition duration for /ba/ and /wa/ were overlapping. In addition, the magnitude of the difference between average /ba/ and /wa/ transition durations increased with decreases in speaking rate. This is because as rate of speech decreased so that syllable duration increased, there was little change in the initial transition duration of /ba/, but a considerable increase in the initial transition duration of /wa/. Given the overall pattern of results, the transition duration that could optimally distinguish /ba/ from /wa/ was not constant, but increased with syllable duration. This is in accord with Miller and Liberman's (1979) finding that when listeners identify /ba/ and /wa/ on the basis of transition duration, they do so in relation to the duration of the syllable.
将音节开头的塞音/b/与半元音/w/区分开来的声学特性之一是起始共振峰过渡的时长；以/b/开头的音节的过渡时长比以/w/开头的音节短。本实验通过研究四名男性说话者发出的/ba/和/wa/的音样，探究了/b/和/w/的过渡时长随语速变化的方式。在任何给定的语速下，/wa/的过渡平均比/ba/的过渡长，不过综合所有语速来看，/ba/和/wa/的过渡时长分布存在重叠。此外，/ba/和/wa/平均过渡时长的差异幅度随着语速的降低而增大。这是因为随着语速降低，音节时长增加，/ba/的起始过渡时长变化不大，但/wa/的起始过渡时长有显著增加。鉴于整体结果模式，能够最佳区分/ba/和/wa/的过渡时长并非恒定不变，而是随着音节时长增加。这与米勒和利伯曼（1979年）的发现一致，即当听众根据过渡时长识别/ba/和/wa/时，他们是相对于音节时长来进行识别的。
