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

Abstract

Abstract-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.

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

“…In Ref. [4] piezoelectric patch actuators were shown to produce control actions not strong enough for glass panels (which has rather high stiffness). Instead piezoelectric stack actuators (PZT) are the best approach for this purpose [5], because they can provide high forces with very low displacements.…”

First Numerical and Experimental Results on Active Controlled Glazed Facades

“…[3] for simply supported bi-dimensional plates in the MatLab TM environment and comparing the vibration field generated by a disturbing noise of magnitude 100 dB with the maximum force provided by both kinds of actuators driven at the voltage of 100 V allowed for standard PZT actuators, it came out that single PZT thin patches were not able to contrast vibrations induced by the chosen disturbance ( Fig. 3) [1]. Therefore, in the following paragraphs the effects of stack actuators on glass panels will be investigated, demonstrating that they can provide forces strong enough to contrast the action of such disturbances.…”

“…It is assumed that the aforementioned rectangular simply supported window is stroked by a harmonic wave at 140 Hz, whose noise level is reasonably the one that could be generated by a lorry traveling at low distance and at a speed of 70 km/h equals to 85 dB, and the mode (1,3) is the most excited. Fig.…”

“…This work is the direct prosecution of the preliminary analyses on the integration of an automated active control system in building glazed facades that was presented in ref. [1], aimed at improving Sound Transmission Loss (STL) of glazed facades. The 89/106/CEE European Directive, has made protection against noise a compulsory requirement for buildings.…”