The invention relates to a sound-attenuating ear plug, comprising an elongate elastic body (103) adapted to be inserted at least partially into an auditory meatus. A foil (117) which is rounded in the longitudinal direction (115) of the body (103) and which is extended transversely of this longitudinal direction (115) is responsible for the major part of the sound-attenuating effect of the ear plug. The invention also relates to a method of manufacturing such an ear plug.