Linguistic factors affecting timing in Korean with application to speech synthesis

This paper describes the results of a study of the phonetic and phonological factors affecting the rhythm and timing of spoken Korean. Stepwise construction of a CART model was used to uncover the contribution and relative importance of phrasal, syllabic, and segmental contexts. The model was trained from a corpus of 671 read sentences, yielding 42,000 segments each annotated with 69 linguistic features. On reserved test data, the best model showed a correlation coefficient of 0.73 with a RMS prediction error of 26 ms. Analysis of the classification tree during and after construction shows that phrasal structure had the greatest influence on segmental duration. Strong lengthening effects were shown for the first and last syllable in the accentual phrase. Syllable structure and the manner features of surrounding segments had smaller effects on segmental duration. The model has application within Korean speech synthesis.