Patent ID: 6648750
Filing Date: 2003-11-18
Classification: F24F,G10K,Y10S

Abstract:
A ventilation assembly comprising a ventilation passageway having two ends, one said end being locatable for communication with an interior space, the other said end being locatable for communication with a further space exterior to the interior space for passively permitting ventilation between the interior and exterior spaces, and an anti-sound system for reducing level, at a location in the interior space, of noise incident upon the passageway in the exterior space;wherein the anti-sound system includes at least one electromagnetic sound generator as well as a piezoelectric or electrostatic sound generator, the electromagnetic sound generator being adapted to produce sounds in a first frequency range and the electrostatic or piezoelectric sound generator being adapted to produce sounds in a second frequency range, the second frequency range having an upper frequency limit which is higher than an upper frequency limit of the first frequency range.