Speech synthesis device, speech synthesis method, and speech synthesis program

A speech synthesis method comprising,

• by using a voiced utterance likelihood index which is an index indicating a degree of voiced utterance likelihood of each state which represents a phoneme modeled by a statistical method, updating a phoneme boundary position which is a boundary with other phonemes neighboring to the phoneme;
• and
• calculating a duration of each phoneme based on the updated phoneme boundary position, and generating synthesized speech based on the calculated duration of phoneme,
• wherein, when a phoneme before and after a phoneme boundary is an unvoiced sound and a voiced sound, determining whether a state before and after the phoneme boundary indicates a voiced state or an unvoiced state by using the voiced utterance likelihood index, and
• wherein, when the state before and after the phoneme boundary are both determined as voiced state or an unvoiced state, updating the phoneme boundary position to move in a predetermined direction according to the state.

A non-transitory computer readable information recording medium storing a speech synthesis program that, when executed by a processor, performs a method for:

• by using a voiced utterance likelihood index which is an index indicating a degree of voiced utterance likelihood of each state which represents a phoneme modeled by a statistical method, updating a phoneme boundary position which is a boundary with other phonemes neighboring to the phoneme;
• and
• calculating a duration of each phoneme based on the updated phoneme boundary position, and generating synthesized speech based on the calculated duration of phoneme,
• wherein, when a phoneme before and after a phoneme boundary is an unvoiced sound and a voiced sound, determining whether a state before and after the phoneme boundary indicates a voiced state or an unvoiced state by using the voiced utterance likelihood index, and
• wherein, when the state before and after the phoneme boundary are both determined as voiced state or an unvoiced state, updating the phoneme boundary position to move in a predetermined direction according to the state.