Design and Development of an Active Controlled Window with High Sound Transmission Loss

Improving the sound transmission loss (STL) of glazed facades is needed, as required by the 89/106/CEE European Directive, which imposes high STL values for building facades, whose weak part is generally constituted by the presence of windows, sometimes making them not adequate to observe the recently enacted requirements. As passive means (e.g. double windows and laminated glazing) were shown to be effective for increasing STL levels only in the medium-high frequency range of sound waves, in this paper an active control system for the coverage of a lower set of frequencies is experimented, where traffic and railway noise produces high levels of disturbance. This paper investigates the ASAC control system as applied on an experimental active control window prototype, focusing mainly on a dedicated technology that is able to improve its STL in the low frequency range, whose effectiveness has been shown by both Finite Element analyses and experiments.