回声信号的产生与消除
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M=4001;
fs=8000;
[B,A]=cheby2(4,20,[0.1 0.7]);
Hd=dfilt.df2t([zeros(1,6) B],A);
hFVT=fvtool(Hd);
set(hFVT,'Color',[1 1 1])
H=filter(Hd,log(0.99*rand(1,M)+0.01).*sign(randn(1,M)).*exp(-0.002*(1:M))); H=H/norm(H)*4;
plot(0:1/fs:0.5,H);
xlabel('Time[sec]');
ylabel('Amplitude');
title('Room Impulse Response');
set(gcf,'Color',[1 1 1]);
load nearspeech
n=1:length(v);
t=n/fs;
plot(t,v);
axis([0 33.5 -1 1]);
xlabel('Time[sec]');
ylabel('Amplitude');
title('Near-End Speech Signal');
set(gcf,'Color',[1 1 1 ]);
p8=audioplayer(v,fs);
playblocking(p8);
load farspeech
x=x(1:length(x));
dhat=filter(H,1,x);
plot(t,dhat);
axis([0 33.5 -1 1]);
xlabel('Time[sec]');
ylabel('Amplitude');
title('Far-End Echoed Speech Signal');
set(gcf,'Color',[1 1 1]);
p8=audioplayer(dhat,fs);
playblocking(p8);
d=dhat+v+0.001*randn(length(v),1);
plot(t,d);
axis([0 33.5 -1 1]);
xlabel('Time[sec]');
ylabel('Amplitude');
title('Microphone Signal');
set(gcf,'Color',[1 1 1 ]);
p8=audioplayer(d,fs);
playblocking(p8);
mu=0.025;
W0=zeros(1,2048);
del=0.01;
lam=0.98;
x=x(1:length(W0)*floor(length(x)/length(W0)));
d=d(1:length(W0)*floor(length(d)/length(W0)));
hFDAF=adaptfilt.fdaf(2048,mu,1,del,lam);
[y,e]=filter(hFDAF,x,d);
n=1:length(e);
t=n/fs;
pos=get(gcf,'Position');
set(gcf,'Position',[pos(1),pos(2)-100,pos(3),(pos(4)+85)]); subplot(3,1,1)
plot(t,v(n),'g');
axis([0 33.5 -1 1]);
xlabel('Time[sec]');
ylabel('Amplitude');
title('Near-End Speech Signal');
subplot(3,1,2)
plot(t,d(n),'b');
axis([0 33.5 -1 1]);
xlabel('Time[sec]');
ylabel('Amplitude');
title('Microphone Signal');
subplot(3,1,3)
plot(t,e(n),'r');
axis([0 33.5 -1 1]);
xlabel('Time[sec]');
ylabel('Amplitude');
title('Output of Acoustic Echo Canceller');
set(gcf,'Color',[1 1 1])
p8=audioplayer(e/max(abs(e)),fs);
playblocking(p8);