To investigate the acoustic characteristics of concentric pipe resonators, the general solution for the acoustic field in the resonators has been derived by using Green's function. The inertial end correction which represents the quantity of an added mass at a hole is also calculated. It is known that a fundamental resonace frequency, in general, is related to the volume of a resonator an the size of a hole. However the volume of resonator is major contributor in determining a resonance frequency, the resonance frequency is also affected by the position of the hole and the shape of the resonator because of the added mass effect. For an efficient noise reduction in concentric pipe resonators with several holes, an appropriate hole distribution is proposed by calculating the transmission loss with varing the position, the number and the size of holes.
The hole impedance, which is one factor in determining the characteristics of perforated acoustic elements, is measured with varing parameters such as diameter and thickness of holes and temperature in the absence of any mean flow.
