This study examines the efficacy of computer-assisted pronunciation training (CAPT) tools in improving learners' production of English vowel sounds. English vowel inventory, characterized by distinctions in length, tension, and diphthongization absent in many other languages, presents a persistent challenge for second language (L2) learners. This paper reviews and systematizes current CAPT methodologies—including acoustic analysis software, automatic speech recognition (ASR), and audiovisual feedback systems—within the IMRAD structure. Findings from a synthesis of recent literature suggest that CAPT, particularly when providing immediate, visual, and formant-based feedback, leads to statistically significant improvements in vowel accuracy and intelligibility compared to traditional methods. The paper concludes with implications for pedagogy and future technological developments.