Karisma Mohapatra, D.P. Jena, Santosha K. Dwivedy
In recent years, there has been growing interest in employing sonic crystals as noise barriers, as periodic arrangement of the scatterers enables sound attenuation within specific frequency range is known as “Bragg band.” Resonant and multi-resonant scatterers are used to enhance acoustic attenuation by generating an additional peak in lower frequency band apart from the Bragg band. However, it remains essential to increase the insertion loss (IL) around both sides of resonant peaks, which is known as passband. To address this issue, both C-shaped and perforated resonant scatterers and combination of concentric C-shaped and perforated scatterers named as CP multi-resonant scatterers are hybridized by installing flat parallel porous panels within the rows of periodic scatterers. The performance of the suggested hybrid configuration has been tested by two-fold approach. Firstly, the IL in broadband frequency range is enhanced ahead of Bragg band and secondly, an attempt has been made to convert the passband to stopband around the resonance peaks in lower frequency band. The numerical model corroborated by experimental results confirmed maximum and broader frequency band of noise attenuation specifically around both sides of resonant peaks and ahead of Bragg band in IL is achieved using the hybrid configuration.