ICA 2010 paper

Natural ventilation and acoustic protection are two conflicting issues. In densely populated cities, open window is nearly not possible because it can provide a path for noise to break-in from external into the buildings. A special window system, namely the plenum window, was investigated in this study for its acoustical insertion loss when the window was not parallel to the road in the urban environment whilst allowing a certain degree of natural ventilation. The acoustic performance of plenum window was studied using a 1:4 scale model and a 5m long source array consisted of 25 six-inch aperture loudspeakers. The positions of sound source from the window are found to be significant in protecting transportation noise based on the trend of insertion loss spectra. The insertion loss of the device was defined by the difference of the average noise level inside the receiver room between opened window and plenum window. There was around 7dBA variation in the insertion loss over the range of source angle studied. The highest insertion loss was about 11dBA and was obtained when the window was nearly parallel to the simulated line source. Plenum window was believed to be a good acoustic window with high practicality in the densely populated urban environment.