In two speech production experiments, we investigated the link between phonetic variation and the scope of advance planning at the word form encoding stage. We examined cases where a word has, in addition to the pronunciation of the word in isolation, a context-specific pronunciation variant that appears only when the following word includes specific sounds. To the extent that the speaker uses the variant specific to the following context, we can infer that the phonological content of the upcoming word is included in the current planning scope. We hypothesize that the time alignment between selection of the phonetic variant in the currently-being-encoded word and retrieval of segmental details of the upcoming word is variable from moment to moment depending on current task demands and the dynamics of lexical access for each word involved. The results showed that the use of a context-sensitive phonetic variant of /t/ (“flapping”) by English speakers reliably increased under conditions which favor advance planning. Our hypothesis was supported by evidence compatible with its three key predictions: an increase in flapping in phrases with a higher frequency following word, more flapping in a procedure with a response delay relative to a speeded response, and an attenuation of the following word frequency effect with delayed responses. This reveals that within speakers, the degree of advance planning varies continuously from moment to moment, reflecting (in part) the accessibility of form properties of individual words in the utterance.

在两个语音生成实验中，我们研究了语音变化与词形编码阶段预先规划范围之间的联系。我们检查了一个单词除了单独的单词发音之外，还有一个特定于上下文的发音变体的情况，该变体仅在以下单词包含特定发音时出现。如果说话者使用特定于以下上下文的变体，我们可以推断即将出现的单词的语音内容包含在当前计划范围内。我们假设当前正在编码的单词中的语音变体的选择与即将到来的单词的分段细节的检索之间的时间对齐是随时变化的，这取决于当前的任务需求和涉及的每个单词的词汇访问动态. 结果表明，在有利于提前计划的条件下，英语使用者使用上下文敏感的 /t/（“扑腾”）语音变体的情况确实增加了。我们的假设得到了与其三个关键预测相符的证据的支持：频率更高的短语中的颤动增加下一个词，在一个过程中会有更多的摆动，相对于一个快速的响应来说，有一个响应延迟，并且随着延迟的响应，下一个词频率效应的衰减。这表明，在说话者内部，预先规划的程度随时都在不断变化，反映（部分）话语中单个词的形式属性的可访问性。