yeah , it a project
i have a work code for cancel the echo:
l=max([length(z);length(x)]);
a=fft([z;zeros(l-length(z),1)]);
b=fft([x;zeros(l-length(x),1)]);
c=real(ifft(a./b));
sound(c,Fs);
it works fine , but they want me use conv function to remove echo , i dont know how :\