clear all; 
close all;
[x,Fs,nbits]=wavread('rockroll.wav');
figure(10),
y1=fft(x);
plot(abs(y1))
[xt1,Fs]=wavread('rockroll.wav');
N=max(size(xt1));
Ts=1/Fs;
t=[0:Ts:(N-1)*Ts];
F=fft(xt1,8192)/N;
Xf1=2*abs(F);
SS=Xf1.*conj(Xf1)/8192;
Freq=Fs*(0:4096)/8192;
figure(1),
subplot(211),plot(Freq,xt1(1:4097),'r'),
title('TIME Domain signal','color','r')
subplot(212),plot(Freq,abs((SS(1:4097))),'r'),
title('Frequency Domain signal','color','r')
title('Frequency Domain','color','r')
ylabel('Voice FREQUENCY DOMAIN','color','r');
xlabel('Frequency/Hz','color','r');
grid on;
zoom on;
fhz1=[0,400,400,4000,4000,11025];
m=[0,0,1,1,0,0];
fhz0=fhz1./(Fs/2);
b=fir2(100,fhz0,m,chebwin(101,20));
tool=[0:11025];
tool2=freqz(b,1,tool,Fs);
figure(2),plot(tool,abs(tool2))
xt2=filter(b,1,xt1);
F1=fft(xt2,8192)/N;
Xf2=2*abs(F1);
SS2=Xf2.*conj(Xf2)/8192;
soundsc(xt2,Fs);
figure(3),
subplot(211),plot(Freq,xt2(1:4097),'r'),
title('TIME Domain signal','color','r')
subplot(212),plot(Freq,abs((SS2(1:4097))),'r'),
title('Frequency Domain signal','color','r')
title('Frequency Domain','color','r')
ylabel('Voice FREQUENCY DOMAIN','color','r');
xlabel('Frequency/Hz','color','r');
wavwrite(xt2,Fs,'zz_cheb.wav');
grid on;
zoom on;