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

A speech processing device comprising:

• a storage unit configured to store a phase shift band pulse signal obtained by band division of a phase-shifted pulse signal;
• a delay time calculation unit configured to calculate a delay time of the phase shift band pulse signal based on a band group delay parameter in a predetermined frequency band of a group delay spectrum calculated from a phase spectrum of a speech frame at each time;
• a phase calculation unit configured to calculate a phase at a boundary frequency based on the band group delay parameter and a band group delay compensation parameter to compensate phase information generated from the band group delay parameter;
• a selection unit configured to select a corresponding phase shift band pulse signal from the storage unit based on the calculated phase of each band;
• a overlap-add unit configured to generate a phase-shifted excitation signal by delaying the selected phase shift band pulse signals according to the delay time to be overlap-added on each other;
• and
• a vocal tract filter configured to apply a vocal tract filter corresponding to a spectrum parameter calculated for each of the speech frames of input speech and output a speech waveform.