The purpose of this study is to confirm whether Korean students can perceive the difference in duration between singleton and geminate types of words in English and Korean and articulate both of them distinctively. Also, through acoustic analyses we want to identify the duration of geminate structures which are regarded as being categorized into two classes, tautomorphemic and concatenated, itself subdivided into morpheme-boundary and word-boundary geminates. Thus, the current study tested some words which are associated with geminate structures and singletons on American and Korean groups of speakers. The results of our study showed that most Koreans’ articulation deeply relied on the spelling of words without recognizing sound variations according to their specific contexts and was greatly affected by the speech sound system of their mother language.