Integration of an Automated Active Control System in Building Glazed Facades for Improving Sound Transmission Loss

In buildings, windows and glazed facades are often the weak link in protecting the interior from exterior noise. Since passive means for improving the Sound Transmission Loss (STL) of glazed facades are very expensive and are effective only at high frequencies, an active controller that increases the STL in the low frequency range is an attractive approach to reducing the noise level in buildings with glazed facades, guaranteeing the performance required by the 89/106/CEE European Directive, which made protection against noise a compulsory requirement for buildings. Several kinds of active control system of Sound Transmission were recently studied, whose two main applications are known as Active Noise Control (ANC) and Active Structural Acoustic Control (ASAC) systems. This paper concerns the second approach: it is based on the reduction of structural vibration, through the use of actuators bonded on the vibrating surfaces, driven by an automated control system, whose task is minimizing those vibrations, and consequently, radiated sound. A technological study aimed at choosing a suitable solution for the integration of such automated control systems in buildings with glazed facades is studied, and future research developments are planned.