Simplified vented acoustic window with broadband sound transmission loss

Abstract

A vented window design is presented allowing for air ventilation and improved sound reduction for urban traffic noise. The window design aims to be of simple construction, consisting of double-glass cells with a two-sided vent opening and a single internal division that splits the inner cavity into two resonators tuned at about 200 and 400 Hz. The basic window cell is modeled by means of a transmission matrix model, as well as through a finite element simulation. These provide an insight into the physical performance principles of the device, and produce results comparable with the acoustic measurements. Preliminary experiments showed the convenience of covering the resonator openings with flow-resistive absorbing material. This helps in raising the spectral sound transmission dips, improving the single number rating according to ISO 717-1:2020 with a measured weighted sound reduction index Rw(C,Ctr)=18(0;0) dB. The comparative performance of the window related to other windows reported in the literature is shown in a graph relating sound reduction and open ventilation area ratio. A reference performance curve is proposed corresponding to the maximum sound transmission loss of a pure constriction with the same open area. The sound reductions offered by different windows can be compared depending on how much their performance, according to Rw, departs above or below this reference curve. The window design performs according to the reference curve.