109 STUDY ON REDUCTION OF BOOM NOISE ABOUT AGRICULTURAL MACHINERY : CONTROL OF SOUND FIELD IN THE CABIN USING ACOUSTIC DYNAMIC ABSORBER(O.S.2 Vibration and Noise Reduction Technology II)

概要

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The purpose of this paper is to show how to reduce the influence of an acoustic cavity mode about the cabin of agricultural machinery. The cabin has few noise absorption material compared with automobiles because the lack of the place, in which such material can be stationed, and the inferior environment. In this paper, using a hexahedron chamber regarded as the tractor cabin, the acoustic properties are investigated. In acoustic cavity modes, the effect of the resonator tuned to the frequency of the acoustic cavity resonance is examined. It is shown that one can shift the resonance frequencies of acoustic cavity modes by resonators. The characteristic about the shifting of the resonance frequencies in the acoustic cavity mode is similar to that of dynamic absorbers in vibration problems. Consequently, we propose equipping a resonator to control the resonance frequencies of the acoustic cavity modes. By opening and closing the hole between the original chamber and the resonator, one can make the frequencies of acoustic cavity resonance change as the occasion demands. Moreover, the acoustic characteristics corresponding to the actual tractor cabin equipping the resonator, which has the frequency tuned to the frequency of the acoustic cavity modes are analyzed. It is shown that the influence of an acoustic cavity mode can be reducible also in the actual tractor.
一般社団法人日本機械学会の論文
2005-05-31