Acoustic properties of Seoul Korean stops in phrase-initial and word-medial positions

Abstract Phonetic implementations of Seoul Korean stops have been examined mostly in phrase-initial positions, primarily focusing on the tonogenesis-like sound change which involves a shift in the primary acoustic property for differentiating aspirated and lax categories. Word-medial stops have been much less discussed, except in the context of inter-sonorant voicing of lax stops. To address this gap, the current study provides a comprehensive analysis of aspirated, lax, and tense stops in Seoul Korean across three prosodic positions, Intonational Phrase (IP)-initial, Accentual Phrase (AP)-initial (inter-sonorant), and word-medial (also inter-sonorant), considering various acoustic properties, namely, stop burst duration, closure duration, post-stop f0 (fundamental frequency), F1, H1*-H2*, and voicing during closure. Based on experimental and corpus data, we report that Seoul Korean stops show distinct acoustic patterns in phrase-initial versus word-medial positions. In IP- and AP-initial positions, burst duration and f0 are the primary acoustic properties that distinguish the three categories, with H1*-H2* further differentiating tense from non-tense stops. In word-medial position, however, closure duration, voicing during closure, and burst duration emerge as the main distinguishing properties, though some f0 differences between lax and aspirated stops are observed. This f0 difference is especially noticeable in non-high vowel contexts, suggesting that the tonogenesis-like change may be spreading beyond phrase-initial positions. Overall, the acoustic implementation of the Seoul Korean three-way laryngeal contrast is highly dependent on the prosodic position of the stops, with this positional variation being most noticeable for lax stops.