Adaptive correlation window for open-loop pitch
View Patent ↗An approach for adaptively adjusting the correlation window for open-loop pitch determination is presented. Correlation between a windowed reference signal (or target signal) and a candidate signal is maximized under most conditions by sliding the reference window by a delta increment in either direction to capture peak energy. The traditional fixed size of the correlation window is maintained. However, the window slides forward and/or backwards to capture peak energy within the window. The position of the adjusting or sliding window is allowed to shift in a small range or increment in either direction to maximize the energy of the windowed signal thus making sure that at least one peak energy is captured within the window.
1. A method of using a microprocessor for improving pitch determination, the method comprising:
obtaining an input voiced speech signal;
segmenting said input voiced speech signal into a plurality of windows of a sample size for pitch lag determination;
selecting a target window of said plurality of windows at an original position;
calculating a total energy of said target window by summing an energy of each of a plurality of samples within said target window;
sliding said target window in a first direction, with respect to said original position, by a sample to redefine said target window;
computing said total energy of said target window after said sliding;
repeating said sliding and said computing, for a pre-defined number of samples to obtain a total energy for each of said target windows;
determining a maximum total energy among every said total energy obtained from said target windows; and
computing a pitch correlation based on said target window having said maximum total energy.
2. The method of claim 1 , wherein after said repeating and prior to said determining, said method further comprising:
sliding said target window in a second direction opposite to said first direction, with respect to said original position, by a sample to redefine said target window;
computing said total energy of said target window after said sliding said target window in said second direction; and
repeating said sliding said target window in said second direction and said computing, for said pre-defined number of samples to obtain a total energy for each of said target windows.
3. The method of claim 1 , wherein said sliding maintains said sample size for each of said target windows.
4. The method of claim 1 , wherein said computing said total energy includes adding an energy value of an added sample and subtracting an energy value of a removed sample to said target window as a result of said sliding.
5. The method of claim 1 further comprising coding said input voiced speech signal using said pitch correlation.
6. A computer program product comprising:
a computer usable medium having computer readable program code embodied therein for improving pitch determination, said computer readable program code configured to cause a computer to perform:
obtaining an input voiced speech signal;
segmenting said input voiced speech signal into a plurality of windows of a sample size for pitch lag determination;
selecting a target window of said plurality of windows at an original position;
calculating a total energy of said target window by summing an energy of each of a plurality of samples within said target window;
sliding said target window in a first direction, with respect to said original position, by a sample to redefine said target window;
computing said total energy of said target window after said sliding;
repeating said sliding and said computing, for a pre-defined number of samples to obtain a total energy for each of said target windows;
determining a maximum total energy among every said total energy obtained from said target windows; and
computing a pitch correlation based on said target window having said maximum total energy.
7. The computer program product of claim 6 , wherein after said repeating and prior to said determining, said method further comprising:
sliding said target window in a second direction opposite to said first direction, with respect to said original position, by a sample to redefine said target window;
computing said total energy of said target window after said sliding said target window in said second direction; and
repeating said sliding said target window in said second direction and said computing, for said pre-defined number of samples to obtain a total energy for each of said target windows.
8. The computer program product of claim 6 , wherein said sliding maintains said sample size for each of said target windows.
9. The computer program product of claim 6 , wherein said computing said total energy includes adding an energy value of an added sample and subtracting an energy value of a removed sample to said target window as a result of said sliding.
10. The computer program product of claim 6 , wherein after said computing said pitch correlation, said method further comprises coding said input voiced speech signal using said pitch correlation.
11. A speech coding device including a microprocessor for improving pitch determination, the speech coding device comprising elements for:
obtaining an input voiced speech signal;
segmenting said input voiced speech signal into a plurality of windows of a sample size for pitch lag determination;
selecting a target window of said plurality of windows at an original position; calculating a total energy of said target window by summing an energy of each of a plurality of samples within said target window;
sliding said target window in a first direction, with respect to said original position, by a sample to redefine said target window;
computing said total energy of said target window after said sliding;
repeating said sliding and said computing, for a pre-defined number of samples to obtain a total energy for each of said target windows;
determining a maximum total energy among every said total energy obtained from said target windows; and
computing a pitch correlation based on said target window having said maximum total energy.
12. The device of claim 11 , wherein after said repeating and prior to said determining, said device further comprising elements for:
sliding said target window in a second direction opposite to said first direction, with respect to said original position, by a sample to redefine said target window;
computing said total energy of said target window after said sliding said target window in said second direction; and
repeating said sliding said target window in said second direction and said computing, for said pre-defined number of samples to obtain a total energy for each of said target windows.
13. The device of claim 11 , wherein said sliding maintains said sample size for each of said target windows.
14. The device of claim 11 , wherein said computing said total energy includes adding an energy value of an added sample and subtracting an energy value of a removed sample to said target window as a result of said sliding.
15. The device of claim 11 further comprising an element for coding said input voiced speech signal using said pitch correlation.