On the impact of labialization contexts on unit selection speech synthesis

This paper presents a study on coarticulatory labialization and the significance of its respecting/violation during selection and concatenation of speech units in the unit selection speech synthesis. The aim of this study is to improve the overall speech quality, especially to increase the perceptual inconspicuousness between concatenated units. The labialization importance was verified by two listening tests-for phonetic laymen and specialists. To suppress the influence of other factors, both tests contained utterances with specially selected phones in specific contexts with respected and violated labialization. The preference for items with correct labialization was evident, which confirms the benefit of considering coarticulatory labialization in a unit selection speech synthesis.