Design of Sonic Cage to attenuate noise in Mines using Sonic Crystal and Melamine Foam

Abstract

Sonic crystals (SCs) are structures made of sound scatterers periodically arranged in a square or triangular lattice. Recent research on sonic crystals has demonstrated that they are efficient materials for controlling the propagation of sound. They attenuate sound in certain frequency bands due to Bragg scattering across the periodic scatterers. This range of frequencies is known as the bandgap, and it is found that sound propagation is significantly reduced in this bandgap region. Belt conveyors linked sequentially to create extensive pathways across surface mines contribute significantly to noise pollution. Typically, noise emission regulations are surpassed in areas where these conveyors operate, especially at night. The operation of belt conveyors predominantly contributes to the overall noise produced by the technological infrastructure. Hence, it is crucial to aim at decreasing their noise emissions. So, with an aim to attain elevated noise reduction, various intuitive sonic cage designs made of sonic crystals such as rigid scatterers, resonant scatterers, and multi resonant scatterers were suggested and followed by the calculation of free-field insertion loss (IL). Insertion Loss (IL) refers to the decrease in noise level at a specific location resulting from the installation of a noise control device along the sound path between the sound source and that particular location. The novelty of this work is that a class of periodic structures, called the radial sonic crystals are presented, in polar coordinates. The initial investigation shows the insertion loss of the proposed sonic cage followed by calculation of insertion loss of hybrid sonic cage design using melamine foam.