Ventilation barrier with space-coiling channels of varying cross-section for broadband sound insulation

Abstract

Efficient broadband silencing of low-frequency sound (<1000 Hz) while retaining the fluid free-flow remains a challenge in acoustical engineering. Here, a ventilated acoustic barrier, consisting of an unrestricted channel and a space-coiling structure with variable cross-sections, is proposed based on Fano-like interference. With the design of the proposed binary structure, the incident sound energy can be effectively attenuated by 90 % in the range of 377 Hz to 425 Hz and 454 Hz to 518 Hz, even at a relatively large opening rate (airflow rate >73 %). Furthermore, the susceptibility of the bands to geometrical parameters and incidence angles is investigated. The structure parameters are optimized using a genetic algorithm to achieve sound attenuation in a broader band from 400 Hz to 1000 Hz. It is shown that this design demonstrates excellent viability for customizing broadband and processing sound from various directions. Experiments are performed to verify the proposed design, and the results are in agreement with the numerical calculations and theoretical predictions. The developed barrier might be potentially applicable to scenarios desiring for low-frequency noise mitigation and free airflow.