Design and in-situ measurement of the acoustic performance of a metasurface ventilation window

Abstract Recent studies have discovered that acoustic metasurfaces possess great versatility in designing novel acoustic systems. An earlier theoretical study pointed out that acoustic metasurface constructed using an array of resonant-duct unit cells can provide superior sound insulation while allowing air to ventilate through the openings distributed on the surface. By using such a principle, a full-scale metasurface ventilation window is designed and experimentally demonstrated in this study. The primary goal of this paper is to detail the acoustic design methodology for developing this window prototype and to characterize its sound insulation performance in-situ. The dimensions of the metasurface window and its unit cells are tuned based on acoustic Finite Element (FE) analysis to enhance its noise reduction for traffic noise frequency, as well as to increase the single number quantity (SNQ) noise rating. The measured transmission loss (TL) shows a consistent behavior with the prediction in the design frequency range. Comparing the proposed window to a conventional casement window with an equal opening area, the SNQ from measurement for the metasurface window is 22 dB, which is 7 dB higher than the casement window at 15 dB. The substantial improvement shows the benefit of incorporating metasurface concept into the design of sound insulation components, such as building facade, noise barriers, etc.