基于小波阈值对语音信号降噪处理（MATLAB实现）

%加载纯净语音信号 x = wnoise('bumps',8); %加载高斯白噪声 snr=15;%修改含噪信号的信噪比 y=awgn(x,snr,'measured'); %含噪信号的信噪比与均方误差 snro=SNR(x,y) d= MSE(x,y) %小波分解 [c,l]=wavedec(y,6,'sym7'); ca6=appcoef(c,l,'sym7',6); cd6=detcoef(c,l,6); cd5=detcoef(c,l,5); cd4=detcoef(c,l,4); cd3=detcoef(c,l,3); cd2=detcoef(c,l,2); cd1=detcoef(c,l,1); %获得默认阈值% sigma= median(abs(cd1))/0.6745; alpha=2; thr=wbmpen(c,l,sigma,alpha); %软阈值去噪% cd1soft=wthresh(cd1,'s',thr); cd2soft=wthresh(cd2,'s',thr); cd3soft=wthresh(cd3,'s',thr); cd4soft=wthresh(cd4,'s',thr); cd5soft=wthresh(cd5,'s',thr); cd6soft=wthresh(cd6,'s',thr); csoft=[ca6 cd6soft cd5soft cd4soft cd3soft cd2soft cd1soft]; xsoft=waverec(csoft,l ,'sym7'); %硬阈值去噪 cdhard1=wthresh(cd1,'h',thr); cdhard2=wthresh(cd2,'h',thr); cdhard3=wthresh(cd3,'h',thr); cdhard4=wthresh(cd4,'h',thr); cdhard5=wthresh(cd5,'h',thr); cdhard6=wthresh(cd6,'h',thr); chard=[ca6 cdhard6 cdhard5 cdhard4 cdhard3 cdhard2 cdhard1]; xhard=waverec(chard,l,'sym7'); %默认去噪方法% %xd=wdencmp('gbl',x,'db4',3,thr,sorh,keepapp); %新去噪方法% cd1new=newthresh(cd1,thr,0.3); cd2new=newthresh(cd2,thr,0.3); cd3new=newthresh(cd3,thr,0.3); cd4new=newthresh(cd4,thr,0.3); cd5new=newthresh(cd5,thr,0.3); cd6new=newthresh(cd6,thr,0.3); cnew=[ca6 cd6new cd5new cd4new cd3new cd2new cd1new]; xnew=waverec(cnew,l,'sym7'); %计算去噪后的SNR% snrsoft=SNR_singlech(x,xsoft) ds= MSE(x,xsoft) snrhard=SNR_singlech(x,xhard) dh= MSE(x,xhard) snrnew=SNR_singlech(x,xnew) dn= MSE(x,xnew) %画图% figure(1) subplot(311);plot(x); axis([0 1200 -5 10]); xlabel('(a) 原始纯净bumps信号 (采样点)');ylabel('幅度'); subplot(312);plot(y); axis([0 1200 -5 10]); xlabel('(b) 含噪bumps信号 (采样点)');ylabel('幅度'); subplot(313);plot(xsoft); axis([0 1200 -5 10]); xlabel('(c) 软阈值降噪后bumps信号 (采样点)');ylabel('幅度'); figure(2) subplot(311);plot(x); axis([0 1200 -5 10]); xlabel('(a) 原始纯净bumps信号 (采样点)');ylabel('幅度'); subplot(312);plot(y); axis([0 1200 -5 10]); xlabel('(b) 含噪bumps信号 (采样点)');ylabel('幅度'); subplot(313);plot(xhard); axis([0 1200 -5 10]); xlabel('(c) 硬阈值降噪后bumps信号 (采样点)');ylabel('幅度'); figure(3) subplot(311);plot(x); axis([0 1200 -5 10]); xlabel('(a) 原始纯净bumps信号 (采样点)');ylabel('幅度'); subplot(312);plot(y); axis([0 1200 -5 10]); xlabel('(b) 含噪bumps信号 (采样点)');ylabel('幅度'); subplot(313);plot(xnew); axis([0 1200 -5 10]); xlabel('(c) 改进阈值降噪后bumps信号 (采样点)');ylabel('幅度');