Unlike some Asian languages (e.g., Korean), English has lexical stress manifested by four acoustic features: duration, intensity, F0 (pitch), and vowel quality. Lexical stress has been known to have significant influences on native English speakers’ recognition of spoken words. According to Cutler (2015), lexical stress has both suprasegmental and segmental features: Suprasegmental features include duration, intensity, and F0 while vowel quality is considered a segmental feature. However, it is still unclear which lexical features are more responsible for spoken word recognition. This study examined which features, suprasegmental features or vowel quality of English, are a more significant influencer in spoken word recognition using English loanwords in Korean, which lack the prominence of any syllable realized by these features. Additionally, this study investigated the claimed advantage of the strong-weak stress pattern over a weak-strong pattern. To that end, two experiments were conducted. First, a parallel acoustic comparison was made between disyllabic English words and their corresponding English loanwords in Korean in order to investigate whether Korean has lexical stress features similar to those of English. 10 Korean and 10 English native speakers read 20 disyllabic words: the English loanwords in Korean by Korean participants and the source English words by American participants. The results showed that the differences of acoustic values between the syllables of the English words were significantly larger than those of the English loanwords. That is, the relative prominence of the stressed syllable over the unstressed syllable in English was not found in Korean. Additionally, the results indicated that Korean does not have a reduced vowel such as /ə/ in English, which is a critical feature of English vowel quality. In Experiment II, 16 English loanwords were used to create three versions of a spoken word recognition experiment, which was administered using the online survey platform, Qualtrics. Each version had a different type of manipulation: unmanipulated English loanwords, English loanwords with suprasegemental manipulation or English loanwords with vowel quality manipulation. 117 American English hearers identified the spoken words of one of the versions assigned to them; their success rates and reaction times (RT) were recorded. A binominal regression test was used for the analysis of success rates, and the Kruskal-Wallis H test for the response times. The results indicated that as far as success rates are concerned, both suprasegmental features and vowel quality play a role in recognizing spoken English words. However, when these two features were compared, vowel quality seemed to be a much stronger player. As for stress patterns, no significant differences were found in success rates across the three sets of manipulation. Moreover, this study did not find any significant difference in RTs either across the three manipulation sets or the two stress patterns. This study offered many applied implications in ESL, especially for teaching English pronunciation in Korea.