In this study, the resonant frequency of Helmholtz resonator is calculated more explicitly using three dimensional analysis method. In classical analysis method, the resonance frequency is calculated with the mass of neck and the stiffness of cavity. But, additional impedance is defined in three dimensional analysis method and equivalent neck length is also calculated. Where equivalent neck length is the function of the geometry of cavity and position of neck and the sufficient number of modes is needed for conversency. Resonant frequencies of various Helmholtz resonators are taken with experiments, and is compared to three dimensional results and classical analysis. In experiments, transfer function of Helmholtz resonator is measured to get the resonant frequencies.
