Lee W., Lee J., Son S.

An acoustic total or partial enclosure is widely used to reduce the sound pressure level propagating from a noise source. However, the performance of the acoustic enclosure is decreased by its inherent limitations such as temperature rise or acoustic pressure build-up inside the enclosed acoustic field. In general, a silencer is installed to overcome these limitations, for large amount of air can be exchanged through it. In this reason, a parallel baffle-type duct silencer with acoustic resonators is studied to reduce the transmitted noise from a transformer. In this silencer, the high-frequency components of the transmitted noise over 360Hz are effectively absorbed by the parallel baffles and the other ones, 120 and 240 Hz, are reduced due to the presence of Helmholtz resonators. Large sound-attenuation is achieved by applying the silencer to the large transformers in a substation