A numerical investigation on the sound insulation of ventilation windows

Finite element method (FEM) with verified model definitions is implemented to characterize the airborne sound transmission. An acoustic cavity with rigid-boundaries is used to simulate the diffuse field on the source side of the window, with its diffuseness verified with the pressure field uniformity. On the receiver side, a free field with an infinite baffle is assumed to capture the transmitted sound power. The Sound Reduction Index (SRI) is calculated from the difference between the source and receiving sound power levels in the one-third octave band. Using the proposed model, different ventilation window configurations, consisting of partially open single glazing, double glazing with staggered openings and that with sound absorbers are systematically investigated. Parametric studies are carried out to investigate the effects of various window dimensions and absorber parameters. Simple formulas are proposed for estimating the SRI in the mid-to-high frequency range, providing guidelines for engineering designs. The validity of the numerical model is confirmed by comparisons with full-scale experimental results.