clear all;close all; 
fvz=44100; f=440; N=10; 
x=0:1:N*fvz-1; 
noise=rand(1,N*fvz); t=x/fvz; 
val=cos(2*pi*t*f)+noise; 
plot(noise(1:1000)); 
sp=fft(val); 
spsel=sp(f*N+1);
spsel2=sp(N*(fvz-f)+1);
sp(N*(fvz-f)+1)=0;
sp(f*N+1)=0; 
val2=ifft(sp);
figure; 
plot(val2(1:1000)); 
MSE=sum((val2-noise).*(val2-noise))/(N*fvz);
soundsc(val, 44100); display("hram sum+f signal, stlac klavesu"); pause;
soundsc(val2, 44100);display("hram filtrovany sum+f signal");