duct silencer

sound attenuator

In ductwork, a device (usually prefabricated) especially designed to provide much greater sound attenuation than would be provided by an equal length of ductwork; the pressure drop through the device is greater than for an equal length of ductwork.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
Additionally, "fan noise from the air handling equipment can be reduced with fan selection and duct silencers, and structure-borne noise from equipment vibration can be reduced by mounting vibrating equipment on spring isolators made with coiled metal rods or elastomer isolators made of rubber or neoprene," he adds.
The cases showed that adding duct silencers or extending ductwork did not reduce the duct rumble.