Phonemic contrast enhancement in clear speech production: The case of Korean stop production

This study explores the code enhancement aspect of clear speech production. Younger (n=11, 20–29 years old) and older (n=11, 40–60 years old) speakers of Korean produced the three series of Korean stops (aspirated, lenis, fortis) in three different speaking styles: conversational, citation‐form, and clear speech. The production of Korean stops was analyzed for three acoustic properties differentiating the Korean stops, voice onset time (VOT), amplitude difference between the first and the second harmonics (H1‐H2), and fundamental frequency (F0). For both of the younger and older groups, the VOT difference between the aspirated and lenis stops was enhanced in clear speech, in addition to enhanced difference between the aspirated/lenis and fortis stops for H1‐H2. The two groups differed in that only the younger speakers showed a substantial increase in F0 for the production of the aspirated stops in clear speech. Also, there was a substantial degree of interspeaker variability in the size and direction of t...