%filter_demo.m
% Demonstration of filtering on speech signals
% Yao Wang, 1/19/2001

close all
clear all
[y,fs]=wavread('morning.wav');
sound(y,fs);
pause;
figure(1); 
subplot(3,3,1), plot(y);pause;
x=y(10000:12000);pause;
subplot(3,3,2),plot(x);axis([1,2000,-0.1,0.1]); pause;
subplot(3,3,3),psd(y,256,fs);pause;


h1=fir1(10,0.5); %design a filter with cutoff at fs/4
subplot(3,3,4),plot(h1);pause
[hf1,w]=freqz(h1,[1],256); %filter frequency response
subplot(3,3,5),plot(w,abs(hf1));pause
z1=conv(y,h1);
sound(z1,fs);pause
subplot(3,3,6),psd(z1,256,fs);pause
wavwrite(z1,fs,'morning_h1.wav');

h2=fir1(10,0.125); %design a filter with cutoff at fs/8
subplot(3,3,7);plot(h2);pause;
[hf2,w]=freqz(h2,[1],256);
subplot(3,3,8),plot(w,abs(hf2));pause;
z2=conv(y,h2);
sound(z2,fs);pause;
subplot(3,3,9);psd(z2,256,fs);pause
wavwrite(z2,fs,'morning_h2.wav');