--- a
+++ b/pitch_detection.m
@@ -0,0 +1,65 @@
+
+%% Signal Definition
+
+[file, path] = uigetfile('*.wav', 'Select a wave file');
+nameoffile = fullfile(path,file);
+
+[y,fs] = audioread(nameoffile);
+y = y(:,1);
+y = y(fix(10*fs):fix(20*fs));
+
+%% Frames and Windows
+
+frame_size=20;
+frame_shift=10;
+window_length=(frame_size/1000)*fs;
+sample_shift=(frame_shift/1000)*fs;
+no_of_windows = (floor((length(y))/sample_shift)-ceil(window_length/sample_shift));
+f0=zeros(1,no_of_windows);
+maxamp = 0;
+flag_y= envelop_hilbert(y);
+
+%% Autocorrelation
+
+for i=1: no_of_windows
+    
+    sig = y(i*sample_shift:(i*sample_shift)+window_length);
+    thres = flag_y(i*sample_shift:(i*sample_shift)+window_length);
+    activity_flag = max(abs(thres));    
+    
+    if activity_flag == 1                     % discarding low amplitude freq
+        cor = xcorr(sig);
+        [pks,locs] = findpeaks(cor);
+        [midval, midloc] = max(pks);
+        [maxval,maxloc] = max(pks(midloc+1:end));
+        
+        if isequal(maxval,maxloc)
+            f0(i) = 0;
+        else
+            period = (abs(locs(midloc)-locs(maxloc+midloc)));
+            f0(i) = fs / period;
+        end
+    else
+        f0(i) = 0;
+    end
+    
+end
+
+v = f0 .* 4.0526e-2;
+
+%% plots
+t=1/fs:1/fs:(length(y)/fs);
+
+[peaks,locs] = findpeaks(f0,'MinpeakHeight',0.5*max(f0),'MinPeakDistance',50);ylim([0 1200]);xlim([0 2000]);
+
+plot(1:no_of_windows,f0*4.0526e-2,locs,peaks*4.0526e-2,'o');title('Pitch of each window');ylabel('Velocity (cm/s)');xlabel('Windows');
+ylim([0 100]);
+g = zoom;
+g.enable = 'on';
+set(gcf, 'Position', get(0,'Screensize'));
+
+max_velocity = max(peaks)*4.0526e-2;
+Velocity = mean(peaks)*4.0526e-2;
+
+fprintf('\nMax Systolic Peak Velocity     = %.2f cm/s\n',max_velocity);
+fprintf('\nAverage Systolic Peak Velocity = %.2f cm/s\n\n',Velocity);