Abstract: A sound attenuator for reducing noise and vibration generated by flow of air, particularly air laden with moisture, particulates and corrosive substances. The sound attenuator comprises a tubular housing and a layer of sound attenuating material, such as closed-cell polyurethane foam, removably secured in the interior of the tubular housing. A retaining ring is located at each end portion of the housing and retain the attenuating layer therebetween to avoid substantial longitudinal sliding movement of the attenuating layer by the force of air flowing therethrough. If the attenuating layer becomes abraided by particulates or absorbs an undesirable amount of moisture during use, the sound attenuating layer can be removed and replaced.