It is well known that speech rate is correlated with many phonetic variables. The current study aims to obtain a more precise characterization of how phonetic measures covary with speech rate. Specifically, we assess whether there is evidence for linear and/or non-linear relations with rate, and how those relations may differ between phrase boundaries. Productions of English non-restrictive (NRRCs) and restrictive relative clauses (RRCs) were collected using a method in which variation in speech rate is cued by the speed of motion of a visual stimulus. Articulatory and acoustic variables associated with phrase boundaries were analyzed; for each variable, Bayesian regression was used to obtain posterior parameter distributions for a set of generalized linear models. Analyses of posterior predictions showed that phonetic variables associated with a phrase boundary that follows the relative clause (post-RC boundary) were more susceptible to rate variation than those at a boundary that precedes the relative clause (pre-RC boundary). Phonetic variables at the post-RC boundary also showed evidence for non-linear relations with rate, which suggest floor or ceiling attenuation effects at extreme rates. On the other hand, substantial differences between syntactic contexts were found primarily at the pre-RC boundary. A high degree of participant-specificity was observed in F0-related variables.

众所周知，语速与许多语音变量相关。目前的研究旨在更准确地描述语音测量如何随语速变化。具体来说，我们评估是否有证据表明速率与线性和/或非线性关系，以及这些关系在短语边界之间可能有何不同。英语非限制性从句 (NRRCs) 和限制性关系从句 (RRCs) 的产生是使用一种方法收集的，在该方法中，语速的变化由视觉刺激的运动速度提示。分析了与短语边界相关的发音和声学变量；对于每个变量，贝叶斯回归用于获得一组广义线性模型的后验参数分布。对后验预测的分析表明，与关系从句之后的短语边界（RC 后边界）相关的语音变量比关系从句之前的边界（RC 前边界）更容易受到速率变化的影响。RC 后边界处的语音变量也显示出与速率呈非线性关系的证据，这表明极端速率下的地板或天花板衰减效应。另一方面，主要在 RC 之前的边界发现了句法上下文之间的实质性差异。在 F0 相关变量中观察到高度的参与者特异性。RC 后边界处的语音变量也显示出与速率呈非线性关系的证据，这表明极端速率下的地板或天花板衰减效应。另一方面，主要在 RC 之前的边界发现了句法上下文之间的实质性差异。在 F0 相关变量中观察到高度的参与者特异性。RC 后边界处的语音变量也显示出与速率呈非线性关系的证据，这表明极端速率下的地板或天花板衰减效应。另一方面，主要在 RC 之前的边界发现了句法上下文之间的实质性差异。在 F0 相关变量中观察到高度的参与者特异性。