Efficient pitch estimation method
First Claim
1. A method for estimation of pitch of an input acoustic signal within a vocoder analyzer to minimize distortion within a vocoder synthesizer while reducing the complexity of said estimation of pitch, comprising the steps of:
- a) center clipping of said input acoustic signals to remove a plurality of formants from said input acoustic signal to form a center clipped acoustic signal;
b) low-pass filtering of the center clipped acoustic signal to further remove any residual of the plurality of formants from said center clipped acoustic signal to form a filtered acoustic signal;
c) calculating an error function for each pitch within said filtered acoustic signals, wherein said error function is determined by the following equation;
##EQU4## where ##EQU5## Wp is a rectangular windowing function and is ##EQU6## s(n) is the speech or acoustic signal, s(n+p) is the speech or acoustic signal delayed by p samples,Rxx and Rxx are autocorrelation functions for x and y,Rxy is a cross correlation function for x and y; and
d) selecting of said pitch so as to minimize said error function.
2 Assignments
0 Petitions
Accused Products
Abstract
A method and means to estimate the pitch of a speech or acoustic signal within a vocoder begins with the center clipping and low-pass filtering of the speech or acoustic signal to eliminate the formants from the speech or acoustic signal. An error function for each pitch is calculated for each pitch within the speech or acoustic signal. A fast tracking method is used to select the estimated pitch for the pitch or acoustic signal. A final check for the doubling of the pitch will minimize any incorrect estimation of the pitch.
25 Citations
8 Claims
-
1. A method for estimation of pitch of an input acoustic signal within a vocoder analyzer to minimize distortion within a vocoder synthesizer while reducing the complexity of said estimation of pitch, comprising the steps of:
-
a) center clipping of said input acoustic signals to remove a plurality of formants from said input acoustic signal to form a center clipped acoustic signal; b) low-pass filtering of the center clipped acoustic signal to further remove any residual of the plurality of formants from said center clipped acoustic signal to form a filtered acoustic signal; c) calculating an error function for each pitch within said filtered acoustic signals, wherein said error function is determined by the following equation;
##EQU4## where ##EQU5## Wp is a rectangular windowing function and is ##EQU6## s(n) is the speech or acoustic signal, s(n+p) is the speech or acoustic signal delayed by p samples,Rxx and Rxx are autocorrelation functions for x and y, Rxy is a cross correlation function for x and y; and d) selecting of said pitch so as to minimize said error function. - View Dependent Claims (2, 3, 4)
-
-
5. A pitch estimation means within a vocoder analyzer to estimate pitch of an input acoustic signal comprising:
-
a) a center clipping means to remove a plurality of formants from said input acoustic signal to form a center clipped acoustic signal; b) a low-pass filtering means to further remove any residual of the plurality of formants from said center clipped acoustic signal to form a filtered acoustic signal; c) an error function calculating means for determining an error function for each pitch within said filtered acoustic signals, wherein said error function is determined by the following equation;
##EQU7## where ##EQU8## Wp is a rectangular windowing function and is ##EQU9## s(n) is the speech or acoustic signal, s(n+p) is the speech or acoustic signal delayed by p samples,Rxx and Rxx are autocorrelation functions for x and y, Rxy is a cross correlation function for x and y; and d) a pitch selecting means to select pitch of said filtered acoustic signal so as to minimize said error function. - View Dependent Claims (6, 7, 8)
-
Specification