A system (10, 30, 40, 50, 80) for filtering an audio input signal (11, 11a, x), divided into different update intervals, according to parameters varying with the update intervals, to obtain a filtered output signal (y, 15), the system comprising: a first filter unit to filter a first filter input signal (11, x) at least at an initial subinterval ( T l) in a current update interval to obtain a first filter output signal (y', 13), according to parameters associated to the preceding update interval, the first filter unit being configured to scale the parameters along at least the initial subinterval ( T l); and a second filter unit to filter a second filter input signal, at the initial subinterval ( T l), according to parameters associated to the current update interval to obtain a second filter output signal, the second filter unit being configured to scale the parameters along at least the initial subinterval ( T l), wherein the first filter input signal (11, 11a) is based on the audio input signal (x), the first filter output signal is an intermediate signal (y'), the second filter input signal is based on the intermediate signal (y'), and the filtered output signal (y) is based on the second filter output signal, characterized in that the first filter unit (12, 51) is configured to scale the parameters associated to the preceding update interval by a first scaling factor (s k-1) changing towards 0, or a value close to 0, along at least the initial subinterval ( T l), wherein the second filter unit (14, 52) is configured to scale the parameters associated to the current update interval by a second scaling factor (s k) changing from 0, or a value close to 0, toward a value different from 0, or a value more distant from 0 than the value close to 0, along at least the initial subinterval ( T l). a first filter unit to filter a first filter input signal (11, x) at least at an initial subinterval ( T l) in a current update interval to obtain a first filter output signal (y', 13), according to parameters associated to the preceding update interval, the first filter unit being configured to scale the parameters along at least the initial subinterval ( T l); and a second filter unit to filter a second filter input signal, at the initial subinterval ( T l), according to parameters associated to the current update interval to obtain a second filter output signal, the second filter unit being configured to scale the parameters along at least the initial subinterval ( T l), wherein the first filter input signal (11, 11a) is based on the audio input signal (x), the first filter output signal is an intermediate signal (y'), the second filter input signal is based on the intermediate signal (y'), and the filtered output signal (y) is based on the second filter output signal, characterized in that the first filter unit (12, 51) is configured to scale the parameters associated to the preceding update interval by a first scaling factor (s k-1) changing towards 0, or a value close to 0, along at least the initial subinterval ( T l), wherein the second filter unit (14, 52) is configured to scale the parameters associated to the current update interval by a second scaling factor (s k) changing from 0, or a value close to 0, toward a value different from 0, or a value more distant from 0 than the value close to 0, along at least the initial subinterval ( T l).