Abstract: Acoustic pulsations in fluid transmission systems such as gas pipelines, engine exhaust systems and compressed air networks are suppressed by an acoustic filter comprising an enlarged pressure vessel with inlet and outlet conduits arranged such that conduit inlet and outlet openings are at the pressure node of standing pressure waves of the pressure vessel length resonant frequency and odd or even harmonics of the fundamental frequency. The inlet and outlet conduit openings are arranged such that the direction of convection flow and acoustic pulsation modulating flow is transverse to the instantaneous particle velocity of fluid resulting from acoustic pulsations existing in or excitable in the pressure vessel. Inlet and outlet conduits preferably open into the pressure vessel in a generally radial direction with respect to the central longitudinal axis of the vessel.