Sung, Jae-Hyun. 2021. Reduction and enhancement across morpheme boundaries in conversational Korean stops. Studies in Phonetics, Phonology and Morphology 27.3. 425-438. Conversational and spontaneous speech has received increasing attention in recent years, but many instrumental studies have focused on widely spoken languages and their phonetic variabilities in conversational speech. To further enhance our understanding of conversational speech, this study examines phonetic reduction and enhancement in Korean stops from casual conversations compared with read speech, focusing on word-medial stop contrast within and across morpheme boundaries in conversation. The results show that stop contrast is maintained, albeit not uniformly, across all conditions, despite significant acoustic reduction in conversation. Specifically, intensity differences serve as a reliable cue in conversation. VOT serves as the most reliable cue at morpheme boundaries, and closure duration serves as the most robust cue in all conditions. F0, considered to be one of the primary cues in word-initial stops, does not serve as a significant cue for word-medial stops. Findings from this study point to manner-specific phonetic adjustments and boundary effects in conversational speech, which yields both phonetic reduction and enhancement. 

Keywords: spontaneous speech, read speech, boundary effects, Korean stops

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