www.pudn.com > voiceprocessingtoolbox.rar > lowpass.m

maxFreq=1047; 
fs=11025; 
order=10; 
b=fir1(order, maxFreq/(fs/2));  
freqz(b, 1, 100); 
 
figure; 
h=freqz(b, 1, 100); 
subplot(2,1,1); 
plot(10*log10(h.*conj(h))); 
subplot(2,1,2); 
plot(h.*conj(h)); 
 
 
waveFile='welcome.wav'; 
[y, fs]=wavread(waveFile); 
 
fprintf('Press return to hear the original signal...\n'); pause 
sound(y, fs); 
 
y2 = filter(b, 1, y); 
 
fprintf('Press return to hear the low-passed signal...\n'); pause 
sound(y2, fs);