Speech processing device, speech processing method, and computer program product

1. A speech processing device comprising:

an amplitude information generation unit configured to generate amplitude information based on a spectrum parameter sequence calculated for each of speech frames of input speech;

a phase information generation unit configured to generate phase information from a band group delay parameter sequence in a predetermined frequency band of a group delay spectrum calculated from a phase spectrum of each of the speech frames and a band group delay compensation parameter sequence to compensate a phase spectrum generated from the band group delay parameter sequence; and

a speech waveform generation unit configured to generate a speech waveform from the amplitude information and the phase information at each time determined based on parameter sequence time information that is time information of each parameter.

2. The speech processing device according to claim 1 , wherein

the phase information generation unit generates a phase-controlled excitation signal by processing in a time domain.

3. The speech processing device according to claim 1 , wherein

the amplitude information generation unit

calculates an amplitude spectrum based on the spectrum parameter sequence at each time,

the phase information generation unit

calculates a phase spectrum based on the band group delay parameter sequence and the band group delay compensation parameter sequence,

the speech waveform generation unit

generates the speech waveform by generating speech waveforms at the respective times based on the amplitude spectrum and the phase spectrum and synthesizing the generated speech waveforms at the respective times to be overlap-added on each other.

4. The speech processing device according to claim 3 , further comprising:

a noise component spectrum calculation unit configured to calculate a noise component spectrum based on the amplitude information and a noise intensity at each frequency, obtained from a band noise intensity parameter sequence representing a ratio of a noise component in the predetermined frequency band;

a periodic component spectrum calculation unit configured to calculate a periodic component spectrum at each of the frequencies based on the amplitude information and the band noise intensity parameter sequence;

a periodic waveform generation unit configured to generate a periodic component waveform from the periodic component spectrum and the phase spectrum constructed based on the band group delay parameter sequence and the band group delay compensation parameter sequence; and

a noise component waveform generation unit configured to generate a noise component waveform based on the noise component spectrum and the phase spectrum corresponding to a noise signal,

the speech waveform generation unit

generating the speech waveform by generating speech waveforms at the respective times based on the periodic component waveform and the noise component waveform and synthesizing the generated speech waveforms at the respective times to be overlap-added on each other.

5. A speech processing device comprising:

a statistical model storage unit configured to store a statistical model trained using a spectrum parameter calculated for each of speech frames of input speech, a band group delay parameter in a predetermined frequency band of a group delay spectrum calculated from on the phase spectrum of each of the speech frames, and a band group delay compensation parameter to compensate a phase spectrum generated from the band group delay parameter;

a parameter generation unit configured to generate the spectrum parameter, a band group delay parameter, and a band group delay compensation parameter corresponding to an arbitrary input text based on context information corresponding to the input text and the statistical model stored in the statistical model storage unit; and

a waveform generation unit configured to generate a waveform from the spectrum parameter, the band group delay parameter, and the band group delay compensation parameter generated by the parameter generation unit.

6. A speech processing method comprising:

generating amplitude information based on a spectrum parameter sequence calculated for each of speech frames of input speech;

generating phase information from a band group delay parameter sequence in a predetermined frequency band of a group delay spectrum calculated from a phase spectrum of each of the speech frames and a band group delay compensation parameter sequence to compensate the phase spectrum generated from the band group delay parameter sequence; and

generating a speech waveform from the amplitude information and the phase information at each time determined based on parameter sequence time information that is time information of each parameter.

7. A computer program product comprising a non-transitory computer-readable medium including a speech processing program configured to cause a computer to execute:

generating amplitude information based on a spectrum parameter sequence calculated for each of speech frames of input speech;

generating phase information from a band group delay parameter sequence in a predetermined frequency band of a group delay spectrum calculated from a phase spectrum of each of the speech frames and a band group delay compensation parameter sequence to compensate the phase spectrum generated from the band group delay parameter sequence; and

generating a speech waveform from the amplitude information and the phase information at each time determined based on parameter sequence time information that is time information of each parameter.