Active control for panel Transmission Loss improvement

Vibroacoustic comfort is becoming more and more a fundamental requirement for the development of new products in both transport and civil engineering. The demand for improved performance is particularly challenging due to the increasing employment of lightweight composite materials in aircraft panels, vehicle body structures and building partitions. Indeed, composite materials are widely used for their high stiffness-to-weight ratio, although this characteristic, beside a generally low structural damping, implies poor vibroacoustic performances. Viscoelastic or massive treatments are commonly employed to mitigate these drawbacks. With reference to the airborne path, the application of active control is here investigated for improving the panel Transmission Loss at low frequency, where passive treatments are less effective. A time domain model for predicting the Transmission Loss in case of single or diffuse field incidence is presented. The model is validated against experimental measurements performed in a double reverberation chamber. Then, active control is introduced into the model and its effectiveness in increasing the panel acoustic insulation is verified.