Estimation of Air Borne and Solid Borne Sounds Radiated from Enclosures

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1. Computer programs were written to estimate the sound pressure distribution produced when a vibrating surface of a machine was shielded by a panel located adjacent to it. The finite element method and the boundary element method were employed for the estimation. In the last fiscal year, the case was dealt with where the priphery of the space lying berween the vibrating surface and the sound shielding panel was closed by rigid walls. In this fiscal year, the case was dealt with where the periphery was open and the noise could be emitted outside through the periphery as well as through the panel. The programs could also estimate the effect of the sound absorbing materials attached to the panel on the side facing the vibrating surface. The reliability of the estimation made by the programs was examined by comparing the computed results with several analytical results. Computed results were also compared with the experimental ones, and it was found that both results agreed well with each … More other.2. A medhod was deviced to estimate separately the solid borne component and the air borne component of the noise emitted from the surfaces of an enclosure containing a noise and vibration source. First a theory was studied to estimate the amount of the solid borne component on the basis of the acceleration measured at the points where the noise and vibration source was attached to the enclosure. Then experiments were carried out to examine if the theory was proper or not. The enclosue used in the experiments was made up of a steel framework and steel panels. The source could produce noise and vibration with adjusted magnitudes. The solid borne component of the noise measured outside the enclosure during the source operation was estimated by the present method. The result of the estimation was compared with the noise measured when the source was supported free from the enclosure, and the reliability of the methob was examind. In addition a method was derived to estimete the force the source applied to the enclosure. Less