Why are Korean tense stops acquired so early: The role of acoustic properties.

Transcription-based studies have shown that tense stops appear before aspirated or lax stops in most Korean-acquiring children's speech. This order of mastery is predicted by the short lag Voice Onset Time (VOT) values of Korean tense stops, as this is the earliest acquired phonation type across languages. However, the tense stop also has greater motor demands than the other two phonation types, given its pressed voice quality (negative H1-H2) and its relatively high f0 value at vowel onset, word-initially. In order to explain the observed order of mastery of Korean stops, we need a more sensitive quantitative model of the role of multiple acoustic parameters in production and perception. This study explores the relationship between native speakers' transcriptions/categorizations of children's stop productions and three acoustic characteristics (VOT, H1-H2 and f0). The results showed that the primary acoustic parameter that adult listeners used to differentiate tense vs. non-tense stops was VOT. Listeners used VOT and the additional acoustic parameter of f0 to differentiate lax vs. aspirated stops. Thus, the early acquisition of tense stops is explained both by their short-lag VOT values and the fact that children need to learn to control only a single acoustic parameter to produce them.