This study investigates the developmental pathway of the three-way contrasts of word-initial stops in Korean-acquiring children aged 18 to 29 months compared to adults. It identifies acoustic-phonetic parameters, such as voice onset time (VOT), fundamental frequency (F0), and amplitude difference between the first and second harmonics (H1−H2), essential for differentiating these stops. Thirty-five Korean monolingual children (ages 1;6 to 2;6) and 10 Korean adults participated. Linear mixed-effects models analyzed the influence of age group and stop phonation type on these acoustic parameters. Results indicated that phonation type significantly affects VOT and F0, with aspirated stops showing the highest VOT and lenis stops the highest F0. Linear Discriminant Analysis demonstrated that while children effectively distinguished fortis stops, they had difficulty accurately classifying aspirated and lenis stops, indicating overlap in acoustic features. Adult comparisons showed lower F0 and higher H1−H2 values, particularly for lenis phonation. The interaction between age and phonation type was significant for both F0 and H1−H2, with children showing increased sensitivity to aspirated phonation. These findings suggest that young Korean children are beginning to utilize temporal features like VOT for phonation type differentiation, while their control over spectral features remains under development.
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