Active Control of Sound Transmission Through an Aperture in a Thin Wall

Abstract

Apertures, like vents of air-conditioning systems and slits of partially opened windows or doors, are very common in the buildings, and they affect the transmission loss performances of the buildings. This chapter proposes to apply the active noise control technique on a small aperture in a thin wall to reduce noise transmitted through it to the other side. Different configurations of secondary sources and error microphones are investigated. It is found that sound radiation can be effectively reduced with an active noise system at the aperture, and the upper-limit frequencies of effective control are discussed.