Abstract: A short-delay postfilter (13) for postfiltering an encoded or decoded audio signal, specifically a speech signal, the short-delay postfilter having a transfer function F(z) of the form F(z)=D(z)/E(z), where E(z) and (D(z) are polynomials dependent on the variable z, where z is the inverse of the unit delay operator z.sup.-1 used in the z transform representation of transfer functions and wherein the denominator E(z) of the transfer functions H(z) of the audio signal's corresponding production filter (12) is also derived and the numerator D(z) differs from the denominator E(z) and is derived by using a longer period than used for the denominator E(z).