Control of interior noise inside a small enclosure using T-shaped acoustic resonators

A theoretical study of noise control in a small enclosure using T-shaped acoustic resonators is presented by means of acoustic coupling analysis. The T-shaped acoustic resonators consist of two mutually perpendicular tubes. When they are inserted into the enclosure, the re-radiation from their apertures excited by the primary source in the enclosure interacts with the existing sound in the enclosure to effectively attenuate the noise level inside the enclosure. The biggest advantage of the T-shaped acoustic resonator is that its large aspect ratio makes it possible to be integrated into the host structures, which relaxes the space requirement in implementation. A general model describing acoustic interaction between one enclosure and T-shaped acoustic resonators is developed, and analytical solutions of the pressure inside the enclosure and the volume velocity source strength scattering out of the resonator aperture are obtained when a single resonator is involved in coupling. These solutions provide insight into the fundamental physics of the acoustic interaction and lead to a helpful design tool for noise control in a small enclosure by using T-shaped acoustic resonators. Numerical simulations are also carried out to illustrate implementation procedures for noise suppression in a right parallepiped enclosure.