Abstract: The device reduces the intensity of noises with localized outlet like those present in the exhaust pipes of endothermic motors, making use of sound-interferences determined by an elastic vibration by means of springs (10) or (12) or (15) of a rigid rod (6) having its fulcrum in (11) and passing through coupled tubes (1) and (2). The acoustic waves spreading in the exhaust and acting onto blade (7) out of one piece with said rod (6) inside the exhaust pipe (1), determine the vibration of the corresponding blade (8) out of one piece with the opposite part of said rod (6) and housed in the coupled pipe (2) so as to generate vibrations in perfect phase opposition interfering at the exhaust pipe's outlet, thus anulling or strongly reducing the noise.