Previous research has established that phonetics has been marginalized within language teaching, proving to be particularly challenging for learners in EFL contexts. This paper presents EPSSML (https://www.usc.gal/multimlab/), an e-learning platform designed within Mayer's (2008, 2009) Cognitive Theory of Multimedia Learning to instruct English phonetics and phonology in an EFL context. Inspired by prior work (e.g., Clark, 2009; Godwin-Jones, 2009; Hansen Edwards et al., 2021), we examined the efficiency of EPSSML as a Computer Assisted Pronunciation Training (CAPT) resource alongside the students' perceptions of it including gender differences. The scores obtained by 504 Spanish EFL learners in an English phonetics undergraduate course were analyzed comparing performance before and after EPSSML-assisted instruction. The analysis of rated results shows that there is a significant difference between the means of scores of those learners that used and those that did not use the platform, as well as between male and female students. Additionally, 127 students that used EPSSML responded to an online questionnaire on the tool and course methodology. Responses reveal that 91.3% of the learners enjoyed and were very interested in EPSSML and web-mediated phonetic training. The findings demonstrate the importance of CAPT-based instruction and suggestions are also made for additional resources and approaches for its implementation, thereby contributing to the educational shift from traditional, teacher-centered learning methods to blended instructional methodologies in formal and informal settings.