A Simple Method for the Analysis of Deep Cavity and Long Neck Acoustic Resonators

Sound Absorption Characteristics of Air-Gap Systems in Enclosed Cavities

“…To show the validity and accuracy of the closed-form resonant frequency equation, equation (10), approximate resonance frequencies obtained from equation (10) are compared with exact ones obtained by means of plotting equations (2,8), which yield the exact resonant frequencies for the single-gap and double-gap systems respectively. It may be seen in Table 1 that the approximate values agree well with the exact values.…”

“…In most researches on Helmholtz resonators [1][2][3][4][5][6][7][8], the main flow of works has focused on effective sound absorption in a pipe or duct by means of more accurate prediction of their resonant frequencies. It may be said that these sound absorbers may not be efficient when it is shaped for suppressing a cavity resonance at a particular frequency identical to one of the resonance frequencies of an enclosed acoustic cavity.…”

Resonant frequency of an adjustable Helmholtz resonator in a hydraulic system

“…Note that Doria [8] used a square cross-section cavity. Johnson and Estève [17] and Estève and Johnson [10] controlled the resonant frequency of the resonator by changing the length of the resonator's neck with servo motors and Doria [8] controlled the neck length with modular elements. Estève [9] and Estève and Johnson [10,11] also tested an adjustable opening resonator, which controls the resonant frequency by varying the opening diameter of the neck with an adjustable iris diaphragm.…”

“…For example, Matsuhisa et al [28], Kostek and Franchek [21], Doria [8] and Singh et al [38] have done tests with a resonator whose cavity volume is controlled. Note that Doria [8] used a square cross-section cavity. Johnson and Estève [17] and Estève and Johnson [10] controlled the resonant frequency of the resonator by changing the length of the resonator's neck with servo motors and Doria [8] controlled the neck length with modular elements.…”

“…The means of controlling the resonant frequency of a Helmholtz resonator are adjusting the resonator neck dimensions, cavity volume, or both [5]. For example, Matsuhisa et al [28], Kostek and Franchek [21], Doria [8] and Singh et al [38] have done tests with a resonator whose cavity volume is controlled. Note that Doria [8] used a square cross-section cavity.…”