Sound traps are devices used to help absorb or muffle the sound generated within a heating ventilating and air conditioning. The purpose of the sound trap is to minimize the amount of sound that travels through the ductwork usually by projecting the sound back toward the point of origin.
This approach helps to keep the interior areas in which the ductwork opens into different rooms relatively quiet and free of the roar that would otherwise come through the vents whenever the system was in operation.