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The presence of Helmholtz resonance modulates the modes of circular membrane
Author(s)
Toboonchuay, Kajornpop
Date Issued
August 23, 2020
Type
Conference Paper
Abstract
A Helmholtz resonator with a circular membrane is a structure that represents a number of real-life systems: For example, kettledrum with hole, the instrument body of Asian spike fiddles (e.g. Thai Saw-u and Cambodian Tro-u), and some acoustic energy harvesters. In the current study, two coupled equations governing the motions of the membrane and that of the air mass in the sound hole were established and solved based on simple assumptions. It was shown that the resonance frequencies corresponding to the circular modes of the membrane were shifted in the presence of the Helmholtz resonator. Furthermore, an additional circular mode could be observed at the frequency lower than the Helmholtz resonance frequency. To validate the theoretical prediction, an experiment was conducted by using a 3D-printed drum, where the frequency response was measured with an impact hammer and a laser doppler vibrometer. It was found that both the additional resonance and the shift in the existing membrane modes could be observed, which agree well with the predicted values.
Citation
Proceedings of 2020 International Congress on Noise Control Engineering Inter Noise 2020, 2020