Assessment of Noise Attenuation by Thin Reflecting Barriers Using Dispersion Relation Preserving Scheme

Abstract

Here, reduction in acoustic noise due to insertion of thin reflecting barriers has been estimated. Accurate simulations have been performed using numerical methods with a near spectral resolving ability, neutral stability and the physical dispersion relation preserving ($DRP$) nature. Use of high accuracy schemes makes present approach useful in analysis of an acoustic field consisting of acoustic waves with a large frequency band. Present investigation has been carried out for eight geometrically different acoustic barriers and for nine discrete frequencies in the one-third octave band starting from 250 $Hz$ to 1600 $Hz$. Use of high accuracy $DRP$ scheme allows one to compute the complex acoustic field by accurately capturing reflection, diffraction and interference of acoustic waves. Comparison of numerically obtained sound pressure level ($SPL$) distributions at different heights with the available experimental results in the literature shows a good match for the case of $I$-shaped barrier. In order to quantify effects of acoustic source frequencies over a large band, we have extended our analysis for a frequency range of 100 $Hz$ to 5000 $Hz$ for the case of $I$-shaped barrier. Present analysis shows that the thick $T$-shaped barrier and grooved barrier work efficiently in the low and mid frequency range while in the higher frequency range all the barriers are equally effective due to minimal diffraction.