Calculations of the Acoustic Efficiency of Noise Shields Based on the Numerical Solution of the Sound Diffraction Equation

Currently, noise-proof wall screens are widely used in urban development to protect against traffic noise, noise from ventilation equipment installed on the roofs of buildings, as well as from other linear and point noise sources. To assess the acoustic efficiency of such screens at the design stage, a practical calculation method proposed by Z. Maekawa for semi-infinite screens of simple geometric shape is used. At the same time, screens of other complex geometric shapes are widely used in the practice of noise reduction by screening in the absence and presence of various technological openings and holes in them. In this case, the application of the calculation method proposed by Z. Maekava may give significant errors in assessing the acoustic efficiency of shielding. For such cases, the article suggests using a method based on the numerical solution of the sound diffraction equation. A computer program has been developed for the numerical solution of the Fresnel-Kirghoff equation and, based on it, the possibility of solving practical problems is shown. Using the program, the influence of openings and gaps available in screens of finite sizes on the acoustic efficiency of shielding is estimated. The proposed numerical method can be applied at the design stage of complex shaped flat noise shields.