The study investigates whether the relationships between complexity and fluency of English as second language (ESL) learners’ in-class oral presentations as well as their individual differences (ID) and L2 oral proficiency change over time. Individual oral presentations completed by 76 ESL learners were audio-recorded both at the beginning and end of a 15-week semester. Each speech-sample was rated for proficiency by two expert raters using the TOEFL speaking rubric. Linguistic variables included syntactic complexity indices, lexical sophistication indices, and breakdown and speed fluency measures. Learners’ first language background, age, gender, previous L2 learning experiences, and class-levels were the ID variables. The results show that articulation rate was predictive of development in oral proficiency over time, and intermediate learners were more successful in developing their proficiency.

中文翻译：

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英语作为第二语言学习者在课堂环境中口语能力发展的预测因素

该研究调查了英语作为第二语言 (ESL) 学习者课堂口语表达的复杂性和流利度之间的关系，以及他们的个体差异 (ID) 和 L2 口语能力是否随时间而变化。在为期 15 周的学期开始和结束时，对 76 名 ESL 学习者完成的个人口头报告进行了录音。每个语音样本都由两名专家评分员使用托福口语标准进行熟练程度评分。语言变量包括句法复杂度指数、词汇复杂度指数以及分解和速度流利度测量。学习者的第一语言背景、年龄、性别、以前的第二语言学习经历和班级水平是 ID 变量。结果表明，随着时间的推移，发音率可以预测口语能力的发展，