Study on Acoustic Damping Ratio of One Dimensional Sound Field Partitioned with Perforated Plate

Kunihiko Ishihara

Noise control, Sound and acoustics, Natural acoustic damping, Perforated plate, Transfer matrix method

A perforated plate is widely used as an acoustic absorption material for compressors and acoustic barriers for roads and railways. It has been confirmed that the perforated plate suppressed the self- sustained tone generated from heat exchangers like a boiler by using it on a duct wall. The effects of the perforated plate on the natural acoustic frequency of an one dimensional sound field partitioned with the perforated plate has been studied in our previous investigations. In this paper, the effects of parameters such as an aperture ratio, a hole’s length and set positions of the perforated plate in the duct, on the sound pressure level, in other words, acoustic damping are discussed experimentally and analytically. The both results are comparatively agreement. Furthermore it was clarified that the real hole’s diameter d₀₀ should be used in the response analysis and the equivalent hole’s diameter d₀ (d₀=d_00√n, n; Number of holes)　should not be used.

https://dx.doi.org/10.31873/IJEAS.7.08.11