The Use of Scatterer Arrays to Improve the Sound Transmission Loss Across Plenum Windows

Plenum windows have been used recently in residential buildings erected next to busy trunk roads. These windows are able to provide an additional 8 dB traffic noise reduction than the conventional casement windows, but at the same time they can allow for natural ventilation of the residential units they protect acoustically. The window design consists of two parallel glass panes - one at the building façade (outer) and the other in the indoor side (inner). The outer and inner window openings are located on opposite window of the window span so that they, together with the cavity between the two window panes form a passage for air movement, while the window's structure acts as an acoustic filter to attenuate noise. To improve the acoustical performance of this window design, it is proposed in this study to install sound scatterer arrays into the window cavity. It is found from finite-element simulation that such proposal, under appropriate settings, can result in about 4 - 5 dB broadband improvement of traffic noise transmission loss across a plenum window without significant reduction of air movement across the window. The acoustical performance will further be improved without increase in air flow resistance when the scatterer rows are staggered.