Improved interference-type sound barriers: Use of hyperbolic phase modulation

Abstract When sound barriers are constructed in parallel on both sides of a noise source, the reduction in noise through one barrier can be impaired because of constructive interference of sound reflected from the other. To eliminate this drawback, sound barriers with phase gradient surfaces have been designed in previous works. Without using any absorbing material, these barriers feature a linear phase profile with height and work by steering the reflected beam downward when sound impinges on them. Here, another interference-type barrier that possesses a nonlinear hyperbolic phase profile is further proposed, which aims to make the reflected wavefronts converge between the barriers, reducing the amount of noise energy that can escape. Results indicate that such a design has a significantly higher insertion loss than the linear case, and could have application in environmental noise control.