This paper reports on the results of a listening instruction intervention for Japanese EFL university students aimed at improving their ability to correctly discern the phonetic and phonological aspects of English sounds. In the background of this project lies our belief that the phonetic/phonological instructions are likely to be helpful (even) for Japanese EFL students who do not major in English linguistics or literature, although these instructions are usually offered to those who are English majors. The goal of the study, thus, is to show that phonetics/phonology-based English teaching is effective for Japanese EFL students in improving their listening ability in general. To achieve the goal, we utilized a set of exercises devised for a 15-week listening course (i.e., “Sound Focus for Effective Listening”; hereinafter, “Sound Focus”). Sound Focus includes six phonetic/phonological aspects of English that are considered by the authors (= instructors) to be essential and important for improvement of listening ability. The participants were 331 freshmen at a national university: 254 were instructed in a CALL (computer-assisted language learning) classroom situation and 77 in a traditional classroom situation. Sound Focus was given with the help of a learning management system (LMS), Moodle, in the CALL classroom situation. In the traditional classroom, the Sound-Focus materials and listening exercises were provided in the form of paper-based handouts used with a CD. To understand the effects of Sound Focus instruction on student achievement and the difference between the two classroom situations, we conducted pre- and post-listening tests and administered a Can-do-statements questionnaire and a free-description questionnaire. The listening tests, which were based on Sound Focus, measured the improvement in students’ listening ability during the course; the Can-do-statements questionnaire evaluated their confidence in their listening ability; and the free description questionnaire aimed to identify the aspects of the instruction that was positively or negatively accepted by the learners. The results of the pre- and post-listening tests and the Can-do-statements questionnaire were analyzed by two-way repeated-measures ANOVA. The free description questionnaire was analyzed with a text-mining technique (SPSS Text Analytics for Surveys 3.0). The two-way repeated-measures ANOVA analysis on the difference between the scores of the pre- and post-listening tests suggested that students in each classroom situation improved their listening ability. The combined analysis of the results of the pre- and post-test scores and the Can-do-statements questionnaire further suggested that the instruction was effective for students with all levels of confidence. We analyzed the free description questionnaire to explicate what aspect of the instruction showed greater effectiveness. The results revealed that among the instructional materials, including the textbook conversations and TOEIC exercises, Sound Focus was considered by the students to be the most effective for their learning, regardless of their classroom situation. The students in the traditional classroom situation reported that the textbook conversations were also helpful. Regarding the presentation of the instructional materials, on the other hand, learners showed a sharp perceptual difference: Those in the CALL classroom situation accepted the LMS (Moodle) more positively, while in the traditional classroom situation, the presentation of the materials with the help of a projector was negatively scored. The analysis also showed that Moodle was also regarded as the best activity for the improvement of their listening ability among all the classroom activities (e.g., role-play conversations, dictations, shadowing). 本実践報告では,英語を専攻としていない日本の大学1年生を対象とした英語リスニングの授業において,英語の音声学・音韻論的特徴を指導した効果を検証した。授業はSound Focusと名付けた教材を使用し,普通教室またはCALL教室で行われ,教室環境の違いも考慮に入れた効果検証を行った。プレ・ポストテストにおける音声学・音韻論的特徴の聞き取りに関するパフォーマンスの違いと英語に対する自信の自己評価(Can-Do調査)との関連を2要因の分散分析により検討した。また,授業終了時の自由記述もテキストマイニングの手法を用いて検討した。分散分析の結果,Sound Focusを用いた英語音声学・音韻論的な指導の効果は,教室環境(普通教室,CALL教室)の違いにかかわらず,大学1年生の聞き取りパフォーマンスの向上に効果があることがわかった。またテキストマイニングの分析からは,両教室環境に対する学生の認識の違いが示された。