Many previous studies have argued that phonology may leave some phonetic dimensions unspecified in surface representations. We introduce computational tools for assessing this possibility though simulation and classification of phonetic trajectories. The empirical material used to demonstrate the approach comes from electromagnetic articulography recordings of high-vowel devoicing in Japanese. Using Discrete Cosine Transform, tongue-dorsum movement trajectories are decomposed into a small number of frequency components (cosines differing in frequency and amplitude) that correspond to linguistically meaningful signal modulations, i.e. articulatory gestures. Stochastic generators of competing phonological hypotheses operate in this frequency space. Distributions over frequency components are used to simulate (i) the vowel-present trajectories and (ii) the vowel-absent trajectories. A Bayesian classifier trained on simulations assigns posterior probabilities to unseen data. Results indicate that /u/ is optionally produced without a vowel-height specification in Tokyo Japanese and that the frequency of such targetlessness varies systematically across phonological environments.

中文翻译：

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通过语音轨迹的模拟和分类评估表面语音规范

许多先前的研究认为，语音学可能会在表面表示中留下一些未指定的语音维度。我们介绍了通过语音轨迹的模拟和分类来评估这种可能性的计算工具。用于演示该方法的经验材料来自日语中高元音除音的电磁关节造影记录。使用离散余弦变换，舌背运动轨迹被分解为少量频率分量（频率和幅度不同的余弦），这些频率分量对应于具有语言意义的信号调制，即发音姿势。竞争语音假设的随机生成器在这个频率空间中运行。频率分量上的分布用于模拟 (i) 元音存在轨迹和 (ii) 元音不存在轨迹。受过模拟训练的贝叶斯分类器将后验概率分配给看不见的数据。结果表明，在东京日语中，/u/ 可以在没有元音高度规范的情况下选择性地产生，并且这种无目标性的频率在语音环境中系统地变化。