LOW-FREQUENCY PASSIVE NOISE CONTROL USING PERIODIC HELMHOLTZ RESONATOR ARRAYS

Resumo

Passive noise control in specific frequency ranges can be achieved using Helmholtz resonators (HR), which are reactive devices that exhibit distinctive geometry, resulting in impedance variations within the enclosing system. Due to the acoustic resonance in the HR, such variations enable the attenuation of propagating waves within a narrow frequency range. When multiple HRs are periodically arranged in an acoustic system, they produce an acoustic metamaterial that greatly expands the frequency range known as a stop band or band gap, which are band structures where sound waves are not allowed to propagate or attenuated. The aim of this paper is to analyze sound wave attenuation in an acoustic metamaterial consisting of HRs arranged in parallel and in series configurations. For this purpose, methods such as the transfer matrix and conventional finite elements will be employed. Parameter sensitivity analysis of HR geometry will be conducted to maximize the attenuation bandwidth of band gaps through Differential Evolution. An optimization process is also conducted to obtain the best sound attenuation using metrics such as sound transmission loss through the amplitude of the incident and reflected wave. Simulated examples are presented to demonstrate the efficiency and validation of the proposed methods.