LPC spectra should correspond with the envelope of DFT spectra. I plot LPC spectra with matlab. The LPC spectra keep the same shape with the envelope of DFT spectra. But it is larger with a offset than the DFT envelope. Why? Where it go wrong? Here is the matlab script which illustrate it. N = 2560; [x,fs] = wavread('lpc.wav',N); % any speech signal can be used p=12; a = lpc(x,p); X =fft(x); X = X(1:N/2+1)'; X = 10*log10(abs(X).^2); Z = fft(a,N); Z = 1./Z(1:N/2+1); Z = 10*log10(abs(Z).^2); figure; plot(X'); hold on; plot(Z,'r'); grid; offset = 10; figure; plot(X+offset); hold on; plot(Z,'r'); grid;
LPC spectra estimate
Started by ●February 6, 2009