原语音信号
[y,fs,bits]=wavread('C:\Users\Administrator\Desktop\111.wav'); >> sound(y,fs,bits);
>> n=length(y)
n =
92611
>> Y=fft(y,n);
>> subplot(2,1,1);plot(y);
>> subplot(2,1,2);plot(abs(Y));
加噪声
>> [y,fs,bits]=wavread('C:\Users\Administrator\Desktop\111.wav'); >> sound(y,fs,bits);
>> n=length(y)
n =
92611
>> Noise=0.2*randn(n,2);
>> s=y+Noise;
>> sound(s)
>> subplot(2,1,1);
>> plot(s)
>> S=fft(s);
>> subplot(2,1,2);
>> plot(abs(S))
>> title('加噪语音信号的频谱波形')
FIR低通滤波器
fp=1000;fc=1200;As=100;Ap=1;fs=30000;
>> wc=2*fc/fs;wp=2*fp/fs;
>> N=ceil((As-7.95)/(14.36*(wc-wp)/2))+1;
>> beta=0.1102*(As-8.7);
>> Win=Kaiser(N+1,beta);
b=fir1(N,wc,Win);
>> freqz(b,1,512,fs);
>> s_low=filter(b,1,s);
>> plot(s_low);title('信号经过低通滤波器的时域图') >> S_low=fft(s_low,n);
>> plot(abs(S_low));title('信号经过低通滤波的频谱') >> sound(s_low,fs,bits)
>>
IIR低通滤波
>> fp=1000;fc=1200;As=100;Ap=1;fs=30000; >> wc=2*fc/fs;wp=2*fp/fs;
>> [n,wn]=ellipord(wp,wc,Ap,As);
>> [b,a]=ellip(n,Ap,As,wn);
>> freqz(b,a,512,fs);
>> t=filter(b,a,y);
>> T=fft(t,n);
>> subplot(2,1,1);plot(t)
>> subplot(2,1,2);plot(abs(T));title('滤波后的频谱') >> sound(t,fs,bits)。