Semi-active links in double-panel noise barriers

Active control methods have shown their effectiveness in reducing noise transmitted through single- or double-panel barriers. However, when the availability of high-performance processors and energy sources is limited, it is worth considering alternative solutions, including semi-active methods. They can offer considerable levels of noise reduction with limited resources and lower application costs. This paper investigates a novel semi-active control approach for double-panel noise barriers, where bistable links mounted between the panels are structurally coupled, when turned on, or decoupled, when turned off. These semi-active links only require energy when switching between states. The structural couplings significantly alter natural frequencies and mode shapes of the vibroacoustic system. This enables an adaptation of structural response dependent on the noise spectrum, i.e. minimizing the radiation in the targeted frequency bands. Such an approach is especially feasible in case of non-stationarynarrow-band noise, which is very common in real-life. Analysis of experimental results shows that the acoustic radiation of the a noise barrier can be reduced by as much as 16 dB for targeted resonance frequencies.