clc
clear
[y, Fs, nbits, opts] = wavread('JanIvona.wav');
khz=Fs/100;
nOfSamples=size(y,1);
x=1:nOfSamples;
x=x/khz;
partSize=30;%ms
minn=1;
maxx=partSize*khz;
breakNow=false;
iteration=1;
while(1)
    E(iteration)=0;
    Z(iteration)=0;
    if(minn>nOfSamples)
        break
    end
    if(maxx>nOfSamples)
        maxx=nOfSamples;
        breakNow=true;
    end
    odcinek=y(minn:maxx,1);
    for i=1:size(odcinek,1)-1
        E(iteration)=E(iteration)+odcinek(i)*odcinek(i);
        if(odcinek(i)*odcinek(i+1)<0)
           Z(iteration)=Z(iteration)+1 ;
        end
    end
    if(breakNow)
        break
    end
    iteration=iteration+1;
    minn=maxx;
    maxx=minn+partSize*khz;
end
normE=max([abs(max(E)),abs(min(E))]);
normZ=max([abs(max(Z)),abs(min(Z))]);
hold on
plot(x,y');
cosx=1:198./size(E,2):198;
plot(cosx,E./normE,'r');
plot(cosx,Z./normZ,'g');