function [t, f0, avgF0] = pitch(y, fs)
% get the number of samples
ns = length(y);
% error checking on the signal level, remove the DC bias
mu = mean(y);
y = y - mu;
% use a 30msec segment, choose a segment every 20msec
% that means the overlap between segments is 10msec
fRate = floor(120*fs/1000);
updRate = floor(110*fs/1000);
nFrames = floor(ns/updRate)-1;
% the pitch contour is then a 1 x nFrames vector
f0 = zeros(1, nFrames);
f01 = zeros(1, nFrames);
% get the pitch from each segmented frame
k = 1;
avgF0 = 0;
m = 1;
for i=1:nFrames
xseg = y(k:k+fRate-1);
f01(i) = pitchacorr(fRate, fs, xseg);
% do some median filtering, less affected by noise
if i>2 & nFrames>3
z = f01(i-2:i);
md = median(z);
f0(i-2) = md;
if md > 0
avgF0 = avgF0 + md;
m = m + 1;
end
elseif nFrames<=3
f0(i) = a;
avgF0 = avgF0 + a;
m = m + 1;
end
k = k + updRate;
end
t = 1:nFrames;
t = 20 * t;
if m==1
avgF0 = 0;
else
avgF0 = avgF0/(m-1);
end