The Application of Active Noise Control to Hvac Systems

Active silencers have a number of advantages including * Good attenuation of low frequency rumble and roar noises.* They are lighter in weight and occupy less space then their acoustically equivalent passive silencers.* The noise can be cancelled at the mechanical room wall and no external lagging of the duct is then required over areas which are sensitive to noise.0 The active systems can be designed into preferred duct layouts, saving the transition pieces required to and from passive silencers, and generally easing the installation.* They open the way to noise control without using fibrous materials if the system is designed to attenuate the high frequencies without the use of these.* Their energy conservation is a continuing cost saving.