Modeling of Acoustic Resonators and Resonator Systems for Use in Passive Noise Control

• Main Author: Calton, Matthew Franklin
• Format: Others
• Published: BYU ScholarsArchive 2016
• Subjects: resonator; impedance translation; resonator-enclosure coupling; Helmholtz; two-microphone method; lumped element
• Online Access: https://scholarsarchive.byu.edu/etd/9261; https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=10270&context=etd

Acoustic resonators, such as the Helmholtz and quarter-wave resonator, can be used to attenuate unwanted noise in an enclosed space. Classical formulations can be used to approximate resonator performance for a given resonator configuration, but may lack sufficient accuracy for some applications. This research aims to improve the analytical characterization of resonators to provide better correlation to experimental results. Using higher-order approximations and proper end corrections, more accuracy can be obtained in calculating the impedance and resonance frequency of a single resonator, which will then carry over into the overall configuration of the model. The impedance of a system of resonators in parallel is also considered, where the effects of acoustic coupling can be observed. Resonators with complex, non-ideal geometries are explored for applications where space is limited. The effects of tapers and toroidal curves are considered using impedance translation methods. These theoretical predictions are found to compare favorably with empirical data. Coupling between an enclosure and resonator system is explored experimentally. The effects of resonator placement, damping, and relative cavity and enclosure volume are considered. These data are used to design and test a resonator system with 10 dB of attenuation over a bandwidth of 10 Hz.