Hogan J T, Rozsypal A J
J Acoust Soc Am. 1980 May;67(5):1764-71. doi: 10.1121/1.384304.
Previous measurements have indicated that vowels before voiced and voiceless consonants exhibit a systematic duration difference, the former being longer approximately by a 3:2 ratio than the latter. Experiments with synthetic speech have shown that vowel duration is an important cue for the voicing distinction of the following consonant in word-final position. In the present paper the role of this cue is evaluated for natural speech, which may also contain secondary cues for maintaining this distinction. The stimuli, spoken by a female speaker, were 24 English monosyllabic words ending with voiced stops, fricatives, and consonant clusters after intrinsically long and intrinsically short vowels. Duration of the vowel nucleus was systematically reduced using a digital gating technique. Recognition rates as a function of vowel duration were obtained. Category change takes place mainly for intrinsically long vowels and for high vowels in combination with final fricatives alone or in consonant clusters. In other cases, category change cannot be established even after the vowel duration is reduced to only 30% of its original duration. In particular, the presence of a long voice bar for a final voiced stop will make shortening of the vowel perceptually less effective. A multiple regression analysis of the experimental data indicates that in natural speech not only vowel duration, but also voice bar duration, duration of silent closure preceding the final release transient, and duration of the release burst or frication noise, depending on the consonant type, vary in weight as cues for voicing under different vowel- and consonant-type conditions.
先前的测量表明，在浊辅音和清辅音之前的元音呈现出系统的时长差异，前者比后者大约长3:2。合成语音实验表明，元音时长是词尾位置后续辅音浊音区分的重要线索。在本文中，针对自然语音评估了这一线索的作用，自然语音可能还包含维持这种区分的次要线索。由一位女性说话者说出的刺激材料是24个以浊塞音、擦音和辅音丛结尾的英语单音节词，这些词分别接在固有长元音和固有短元音之后。使用数字选通技术系统地缩短了元音核心的时长。获得了作为元音时长函数的识别率。类别变化主要发生在固有长元音以及单独或与辅音丛组合的高元音与最终擦音的情况下。在其他情况下，即使元音时长缩短到其原始时长的仅30%，也无法确定类别变化。特别是，最终浊塞音的长音杠的存在会使元音缩短在感知上效果降低。对实验数据的多元回归分析表明，在自然语音中，不仅元音时长，而且音杠时长、最终释放瞬变之前的无声闭合时长以及释放爆发或摩擦噪声的时长（取决于辅音类型），在不同元音和辅音类型条件下作为浊音线索的权重都会有所变化。
