function [b, a] = aweighting(fs)
%AWEIGHTING return digital A-weighting filter in time domain

num = 7.39705e9 * [1 0 0 0 0];
den = conv([1 129.4], conv([1 129.4], conv([1 676.7], conv([1 4636], conv([1 76655], [1 76655])))));

afilterc = tf(num, den);
afilterd = c2d(afilterc, 1/fs);
b = afilterd.num{1};
a = afilterd.den{1};

end
