Speech synthesis apparatus and method

A non-transitory computer readable storage medium storing instructions of a computer program which when executed by a computer results in performance of steps comprising:

• selecting speaker's parameters one by one for respective speakers and obtaining a plurality of speakers' parameters, the speaker's parameters being prepared for respective pitch waveforms corresponding to speaker's speech sounds, the speaker's parameters including formant frequencies, formant phases, formant powers, and window functions concerning respective formants that are contained in the respective pitch waveforms;
• making formants correspond to each other between the plurality of speakers' parameters using a cost function based on the formant frequencies and the formant powers;
• generating an interpolated speaker's parameter by interpolating, at desired interpolation ratios, the formant frequencies, formant phases, formant powers, and window functions of formants which are made to correspond to each other;
• and
• synthesizing a pitch waveform corresponding to interpolated speaker's speech sounds based on the interpolation ratios using the interpolated speaker's parameter.

A speech synthesis method comprising:

• selecting speaker's parameters one by one for respective speakers and obtaining a plurality of speakers' parameters, by a selecting unit, the speaker's parameters being prepared for respective pitch waveforms corresponding to speaker's speech sounds, the speaker's parameters including formant frequencies, formant phases, formant powers, and window functions concerning respective formants that are contained in the respective pitch waveforms;
• making formants correspond to each other between the plurality of speakers' parameters using a cost function based on the formant frequencies and the formant powers, by a mapping unit;
• generating an interpolated speaker's parameter by interpolating, at desired interpolation ratios, the formant frequencies, formant phases, formant powers, and window functions of formants which are made to correspond to each other, by a generating unit;
• and
• synthesizing a pitch waveform corresponding to interpolated speaker's speech sounds based on the interpolation ratios using the interpolated speaker's parameter, by a synthesis unit.