Mitigation of gun blast noise by surface impedance design

Surface impedance is designed to mitigate gun blast noise with high energy and low frequencies. By corrugating the ground surface with trenches of critical depths, artificially soft surface can be generated at the openings of those trenches inside the ground. If such trenches are enough, the structure can effectively mitigate the propagation of acoustic wave along the ground by destructive interference. Compared with the use of ground shelters, the approach may be cheaper, safer and space efficient. To examine the effectiveness of the model, we develop an efficient numerical solver to solve acoustic wave scattering by the ground. The ground is truncated circularly with a large radius and the trenches are concentrically shaped so that we can treat it as a body of revolution (BOR). Numerical simulations show that the scheme can effectively reduce the sound level at the far zone by selecting appropriate design parameters.