NOISY SIGNAL clear clc   load 1z88153a8.mat sig=sigd;   load white8.mat noise=sigd(1:length(sig));   clear sigd   Esig = sig' * sig;   Enoise = noise' * noise;   noisy_sig = sig + noise*sqrt(Esig/(10*Enoise));   noise = noise*sqrt(Esig/(10*Enoise));   sig = sig/max(abs(noisy_sig));   noise = noise/max(abs(noisy_sig));   noisy_sig = noisy_sig/max(abs(noisy_sig)); y = filter(noise,sig,noisy_sig);   subplot(221) plot(sig) title('Signal original') subplot(222) plot(noise) title('Bruit') subplot(223) plot(noisy_sig) title('Signal bruite') subplot(224) plot(y) title('filtered signal')     sound(noisy_sig)