Experimental study on the performance of a simple noise barrier in presence of a Helmholtz resonator buried in the ground

This study addresses the problem of performance of a noise barrier when a Helmholtz resonator is buried in the ground on the side of the sound source. The noise barrier is a simple upright one and the Helmholtz resonator consists of a series of adjacent containers buried in the ground and tuned by means of tubes connected to the containers at frequencies typical to traffic noise. The study is conducted at a scale model level and comparisons are made on measurements conducted with, and without resonators to investigate the effect of these latter on the reduction (enhancement) of traffic noise that is already reduced through the interposition of a simple barrier between the noise source and the receiver. The investigation shows that the volume of the cavity of the resonator has an effect on the additional reduction of sound at the receiver at low frequencies whereas at high frequencies the resonator has a negative contribution to the overall insertion loss.