Method, apparatus and computer program product for providing real glottal pulses in HMM-based text-to-speech synthesis

1. An apparatus comprising:

a processor; and

a memory including computer program code, the memory and the computer program code configured to, with the processor, cause the apparatus to at least:

select a real glottal pulse from among one or more stored real glottal pulses based at least in part on a property associated with the real glottal pulse;

utilize the real glottal pulse selected as a basis for generation of an excitation signal; and

modify the excitation signal based on spectral parameters generated by a model to provide synthetic speech and by filtering the excitation signal based on spectral parameters generated by a hidden Markov model framework.

2. An apparatus according to claim 1 , wherein the memory including the computer program code is further configured to, with the processor, cause the apparatus to perform an initial operation of estimating the plurality of stored real glottal pulses from corresponding natural speech signals using glottal inverse filtering.

3. An apparatus according to claim 1 , wherein the memory including the computer program code is further configured to, with the processor, cause the apparatus to train the hidden Markov model framework using parameters generated at least in part based on glottal inverse filtering.

4. An apparatus according to claim 1 , wherein the memory including the computer program code is further configured to, with the processor, cause the apparatus to select the real glottal pulse by selecting the real glottal pulse at least in part based on parameters associated with the hidden Markov model framework.

5. An apparatus according to claim 1 , wherein the memory including the computer program code is further configured to, with the processor, cause the apparatus to select the real glottal pulse by selecting a current pulse based at least in part on a previously selected pulse.

6. An apparatus according to claim 1 , wherein the memory including the computer program code is further configured to, with the processor, cause the apparatus to select the real glottal pulse by selecting the real glottal pulse based on a fundamental frequency associated with the real glottal pulse.

7. An apparatus according to claim 6 , wherein the memory including the computer program code is further configured to, with the processor, cause the apparatus to modify the fundamental frequency.

8. An apparatus according to claim 7 , wherein the memory including the computer program code is further configured to, with the processor, cause the apparatus to modify the fundamental frequency by utilizing time domain or frequency techniques for modifying the fundamental frequency.

9. An apparatus according to claim 6 , wherein the memory including the computer program code is further configured to, with the processor, cause the apparatus to select the real glottal pulse by selecting at least two pulses and wherein modifying the fundamental frequency comprises combining the at least two pulses into a single pulse.

10. A method comprising:

selecting a real glottal pulse from among one or more stored real glottal pulses based at least in part on a property associated with the real glottal pulse;

utilizing the real glottal pulse selected as a basis for generation of an excitation signal; and

modifying, via a processor, the excitation signal based on spectral parameters generated by a model to provide synthetic speech and spectral parameters generated by a hidden Markov model framework.

11. A method according to claim 10 , wherein selecting the real glottal pulse further comprises selecting a current pulse based at least in part on a previously selected pulse.

12. A method according to claim 10 , wherein selecting the real glottal pulse further comprises selecting the real glottal pulse based on a fundamental frequency associated with the real glottal pulse.

13. A method according to claim 10 , further comprising an initial operation of estimating the plurality of stored real glottal pulses from corresponding natural speech signals using glottal inverse filtering.

14. A computer program product comprising at least one computer-readable non-transitory storage medium having computer-executable program code portions stored therein, the computer-executable program code portions comprising:

program code instructions for selecting a real glottal pulse from among one or more stored real glottal pulses based at least in part on a property associated with the real glottal pulse;

program code instructions for utilizing the real glottal pulse selected as a basis for generation of an excitation signal; and

program code instructions for modifying the excitation signal based on spectral parameters generated by a model to provide synthetic speech and spectral parameters generated by a hidden Markov model framework.

15. A computer program product according to claim 14 , wherein the program code instructions for selecting the real glottal pulse include instructions for selecting a current pulse based at least in part on a previously selected pulse.

16. A computer program product according to claim 14 , wherein the program code instructions for selecting the real glottal pulse include instructions for selecting the real glottal pulse based on a fundamental frequency associated with the real glottal pulse.

17. A computer program product according to claim 14 , further comprising program code instructions for an initial operation of estimating the plurality of stored real glottal pulses from corresponding natural speech signals using glottal inverse filtering.