The acquisition of Korean word-initial stops.

A number of studies have investigated acquisition of stop voicing contrast in various languages by voice onset time measurement. Korean stops, however, are all voiceless word-initially and are differentiated by multiple acoustic-phonetic parameters resulting in a three-way contrast (fortis, aspirated, and lenis). The present study examines developmental patterns of Korean word-initial stops produced by 40 Korean children aged 2;6 (year; month), 3;0, 3;6, and 4;0 years, and compare the children's productions to those of 10 female adults. Voice onset time, fundamental frequency, and amplitude difference between the first and second harmonics of the post-stop vowel are obtained from monosyllabic near-minimal triplets at three places of articulation (labial, alveolar, and velar). Acoustic measures of children's productions reveal both universal phonetic patterns and phonetic variation associated with articulatory complexity specific to Korean. Language-specific fundamental frequency variation begins to emerge as early as 2;6, but appears to be mastered later than the voice onset time distinction. In comparison to the adults, young Korean children exhibit greater overlap across stop categories, and the acoustic overlap decreases over age. Results suggest that language-specific phonetic details as well as universal patterns should be examined to provide a better understanding of the speech sound development of a given language.