Estimation of Pitch from Speech Signals Using Autocorrelation Algorithm

Hello,

I want to detect speech signals pitch frequency using autocorrelation algorithm. I have a MATLAB code but the results are wrong. I would be grateful if you could solve the mistake in my code.

[y,Fs]=audioread('Sample1.wav'); 
y=y(:,1);
auto_corr_y=xcorr(y); 
subplot(2,1,1),plot(y) 
subplot(2,1,2),plot(auto_corr_y)
[pks,locs] = findpeaks(auto_corr_y);
[mm,peak1_ind]=max(pks);
period=locs(peak1_ind+1)-locs(peak1_ind);
pitch_Hz=Fs/period

Thank you for your help in this matter.

[Samia Dilbar]

Hey did you resolve it ? help me in this

[Nene Pfupa]

did you find the answer.help me too.

Answer 1

[Mathieu NOE]

hello

this is a modified version of the code . The autocorrelation ouput will have a major peak at sample = M (x axis) and is symmetrical around this value. So first modification is to keep the autocor vector second half only, starting at sample = M ; what we are looking for is the next peak to get the pitch value

[y,Fs]=audioread('Sample1.wav'); 
y=y(:,1);
auto_corr_y=xcorr(y); 
M = length(y);
%   C = XCORR(A), where A is a length M vector, returns the length 2*M-1
%   auto-correlation sequence C. The zeroth lag of the output correlation
%   is in the middle of the sequence, at element M.

auto_corr_y = auto_corr_y(M:M+100); % keep only the second half (starting at sample = M which is the max peak output)  and show + 100 samples
auto_corr_x = 1:numel(auto_corr_y);

[pks,locs] = findpeaks(auto_corr_y);
subplot(2,1,1),plot(y) 
subplot(2,1,2),plot(auto_corr_x,auto_corr_y,locs,pks,'dr')
pitch_Hz=Fs/locs(1)

[Vanya Meegan]

 error unrecognized function or variable nume1

[Mathieu NOE]

hello

numel was introduced quite recently

you can replace it with length for older matlab releases.

[y,Fs]=audioread('Sample1.wav'); 
y=y(:,1);
auto_corr_y=xcorr(y); 
M = length(y);
%   C = XCORR(A), where A is a length M vector, returns the length 2*M-1
%   auto-correlation sequence C. The zeroth lag of the output correlation
%   is in the middle of the sequence, at element M.
auto_corr_y = auto_corr_y(M:M+100); % keep only the second half (starting at sample = M which is the max peak output)  and show + 100 samples
auto_corr_x = 1:length(auto_corr_y);
[pks,locs] = findpeaks(auto_corr_y);
subplot(2,1,1),plot(y) 
subplot(2,1,2),plot(auto_corr_x,auto_corr_y,locs,pks,'dr')
pitch_Hz=Fs/locs(1)