This empirical study examined error performance in Hausa vowel production by Yoru?ba? speakers, using a quantitative approach. The aim was to compare two groups in the final-year National Certificate in Education in producing Hausa shared and unshared vowels, and to assess gender and institutional differences across five colleges (ABK, ACE, IKR, ORO, and ORO) to determine whether significant variation exists in the first and second syllables. A cross-sectional design was employed with 110 Yoruba-speaking participants aged 18 and above who were learning Hausa in the five colleges of education in southwestern Nigeria, selected purposively. Stimuli were drawn from the Online Hausa-English Dictionary, questionnaires were administered, and production tasks were audio-recorded. Data were analyzed with independent t-tests and ANOVA in line with Flege and Bohn’s Revised Speech Learning Model (SLM-r). Results show that the t-test p-values are not significant in the first syllable (p > .482) and the second syllable (p > .051), while producing vowel length. When comparing the genders, the first syllable remained non-significant (p > .042). In contrast, the second syllable showed a significant difference between males and females (p < .004), indicating gender effects on vowel production in the second syllable. Across five schools, ANOVA yielded a highly significant overall difference (p = .000), with mean scores ranging from a low of 7.191 to a high of 23.58, suggesting variability in performance by institution. The study attributes such errors to linguistic, environmental, and L1 influence factors. The Hausa language teachers should focus on vowels with high error rates to improve second-language intelligibility.