本論文旨在分析台灣英語學習者對習得美式英語語音時長類型，從聲學測量討論四個時長變項，分別為音節長度、母音弱化、連音時長以及子音串時長，並提出新的變異指標以比較變項間的差異，以此診斷出學習者習得英語語音時長之困難。在語言類型分類上，國語是聲調語言，以音節時長為導向；而英語是重音語言，以重音時長為依據。由於國語和英語韻律節奏上的差異，分析二者間之中介語對語言習得有重要價值。主要研究結果如下：英語母語人士之音節時長的變異性大於台灣英語學習者，此結論支持了先前之假設：英語較偏向重音時長之韻律，台灣英語學習者受母語影響，較偏向音節時長之韻律。台灣英語學習者之音節時長類型和英語母語人士極為不同，美式英語較常出現弱化母音，而台灣英語學習者較偏好使用全母音，因而造成韻律之差異。此外，台灣英語學習者的說話速度較慢，子音母音間的連音時長較英語母語人士長，單字與單字之間常插入短暫停頓或聲門塞音。從四組受試者中發現其子音串簡化的主要策略為子音刪除，而在台灣學習之低成就英語學習者則特別偏好子音插入。

This study investigates the timing properties of English spoken by Taiwanese learners, which has been predicted as syllable-timed, and American English, which is usually assumed to be stress-timed. Syllable duration, vowel reduction, linking duration, and consonant cluster duration were acoustically measured and compared. A new variability index (VI) was proposed and calculated. The results show a significant disparity in syllable duration and syllable-to-syllable variation between American English and English spoken by Taiwanese learners. The higher frequency of reduced syllables with a schwa in American English contributes to the difference between American English and that spoken by Taiwanese learners. Taiwanese learners’consonant-vowel linking duration is much longer than that of the native speakers.Some word boundaries are maintained through the insertion of short pauses and glottal stops. The dominant strategy for consonant cluster simplification across the four groups is consonant deletion, but the Taiwanese learners with low English proficiency evinced a specific preference for consonant epenthesis.