Havenhill Jonathan, Do Youngah
Department of Linguistics, Georgetown University, Washington, DC, United States.
Department of Linguistics, University of Hong Kong, Hong Kong, Hong Kong.
Front Psychol. 2018 May 15;9:728. doi: 10.3389/fpsyg.2018.00728. eCollection 2018.
What are the factors that contribute to (or inhibit) diachronic sound change? While acoustically motivated sound changes are well-documented, research on the articulatory and audiovisual-perceptual aspects of sound change is limited. This paper investigates the interaction of articulatory variation and audiovisual speech perception in the Northern Cities Vowel Shift (NCVS), a pattern of sound change observed in the Great Lakes region of the United States. We focus specifically on the maintenance of the contrast between the vowels /ɑ/ and /ɔ/, both of which are fronted as a result of the NCVS. We present results from two experiments designed to test how the NCVS is produced and perceived. In the first experiment, we present data from an articulatory and acoustic analysis of the production of fronted /ɑ/ and /ɔ/. We find that some speakers distinguish /ɔ/ from /ɑ/ with a combination of both tongue position and lip rounding, while others do so using either tongue position or lip rounding alone. For speakers who distinguish /ɔ/ from /ɑ/ along only one articulatory dimension, /ɑ/ and /ɔ/ are acoustically more similar than for speakers who produce multiple articulatory distinctions. While all three groups of speakers maintain some degree of acoustic contrast between the vowels, the question is raised as to whether these articulatory strategies differ in their perceptibility. In the perception experiment, we test the hypothesis that visual speech cues play a role in maintaining contrast between the two sounds. The results of this experiment suggest that articulatory configurations in which /ɔ/ is produced with unround lips are perceptually weaker than those in which /ɔ/ is produced with rounding, even though these configurations result in acoustically similar output. We argue that these findings have implications for theories of sound change and variation in at least two respects: (1) visual cues can shape phonological systems through misperception-based sound change, and (2) phonological systems may be optimized not only for auditory but also for visual perceptibility.
促成（或抑制）历时性语音变化的因素有哪些？虽然有充分记录表明语音变化是由声学因素驱动的，但关于语音变化的发音和视听感知方面的研究却很有限。本文研究了美国五大湖地区观察到的一种语音变化模式——北方城市元音转移（NCVS）中发音变化与视听语音感知的相互作用。我们特别关注元音/ɑ/和/ɔ/之间对比的维持，这两个元音在NCVS过程中都发生了前移。我们展示了两个旨在测试NCVS如何产生和被感知的实验结果。在第一个实验中，我们展示了对前移的/ɑ/和/ɔ/发音的发音和声学分析数据。我们发现，一些说话者通过舌位和唇形圆展的组合来区分/ɔ/和/ɑ/，而另一些说话者仅通过舌位或唇形圆展来区分。对于仅沿着一个发音维度区分/ɔ/和/ɑ/的说话者来说，/ɑ/和/ɔ/在声学上比进行多种发音区分的说话者的/ɑ/和/ɔ/更相似。虽然所有三组说话者都在一定程度上维持了元音之间的声学对比，但问题在于这些发音策略在可感知性方面是否存在差异。在感知实验中，我们测试了视觉语音线索在维持这两个音之间对比中起作用的假设。该实验结果表明，/ɔ/以不圆唇方式发音的发音配置在感知上比/ɔ/以圆唇方式发音的配置弱，尽管这些配置在声学上产生的输出相似。我们认为，这些发现至少在两个方面对语音变化和变异理论具有启示意义：（1）视觉线索可以通过基于错误感知的语音变化塑造音系，（2）音系不仅可能为了听觉可感知性而且可能为了视觉可感知性而得到优化。
