Speech synthesis system having artificial excitation signal

A speech synthesis system for synthesizing a speech signal corresponding to an input speech signal, based on a pitch value, a spectral envelope and a noise signal of the input speech signal, the system comprising:

• a glottal pulse generator configured to generate a time series of glottal pulses based on the pitch value;
• a time domain to frequency domain transform circuit configured to generate a glottal pulse magnitude spectrum based on the time series of glottal pulses;
• a shaping circuit configured to shape the glottal pulse magnitude spectrum in accordance with the spectral envelope and generate a shaped glottal pulse magnitude spectrum;
• a harmonic null adjustment circuit configured to reduce harmonic nulls in the shaped glottal pulse magnitude spectrum based on background noise signal, to generate a null-adjusted synthesized speech spectrum;
• a frequency domain to time domain transform circuit configured to transform the null-adjusted synthesized speech spectrum to the time domain and generate a null-adjusted time-series speech signal;
• and
• an overlap and add circuit configured to synthesize the speech signal based on the null-adjusted time-series speech signal.

A method for synthesizing a speech signal corresponding to an input speech signal based on a spectral envelope of the input speech signal, the method comprising:

• generating a time series of glottal pulses;
• transforming the time series of glottal pulses into a glottal pulse magnitude spectrum;
• shaping the glottal pulse magnitude spectrum in accordance with the spectral envelope to generate a shaped glottal pulse magnitude spectrum;
• reducing harmonic nulls in the shaped glottal pulse magnitude spectrum to generate a null-adjusted synthesized speech spectrum;
• transforming the null-adjusted synthesized speech spectrum to the time domain to generate a null-adjusted time-series speech signal;
• and
• processing the null-adjusted time-series speech signal on a frame-by-frame basis to synthesize the speech signal.

A speech synthesis system adapted to synthesize a speech signal corresponding to an input speech signal, based on a spectral envelope of the input speech signal, the system comprising:

• a glottal pulse generator configured to generate a time series of glottal pulses;
• means for transforming the time series of glottal pulses into the frequency domain to generate a glottal pulse magnitude spectrum;
• means for shaping the glottal pulse magnitude spectrum in accordance with the spectral envelope to generate a shaped glottal pulse magnitude spectrum;
• means for reducing harmonic nulls in the shaped glottal pulse magnitude spectrum to generate a null-adjusted synthesized speech spectrum;
• means for transforming the null-adjusted synthesized speech spectrum into the time domain to generate a null-adjusted time-series speech signal;
• and
• an overlap and add circuit configured to synthesize the speech signal based on the null-adjusted time-series speech signal.