An acoustic filter including a valve system with acoustic valves arranged in a sound passage for controlling the acoustic resistance of respective apertures based on a control signal for selecting an attenuation of a sound pressure level of transmitted sound compared to that of received sound. The acoustic filter is adapted to provide the selection of the attenuation from a sequence of predetermined attenuations based on a selection of the control signal. Each attenuation in the sequence corresponds to acoustic valves providing the apertures with a respective predetermined acoustic resistance, wherein the acoustic resistances of subsequent attenuations in the sequence are adapted to correspond with a linear increase or decrease in the attenuation of the sound in decibels.