%noise suppression
function gain=noise_sup(gain,G_n)
max_noise=20;
max_atten=6;
if G_n>max_noise;
   G_n=max_noise;
end
gain_lev=gain-G_n-3;
if gain_lev>0.001
   suppress=-10*log10(1-10^(-0.1*gain_lev));
   if suppress>max_atten
      suppress=max_atten;
   end
else
   supress=max_atten;
end
gain=gain-max_atten;