二重壁内部気体の音響特性が透過損失へ及ぼす影響(機械力学,計測,自動制御)

概要

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The dependence of transmission loss (TL) of a double-wall structure on the characteristics of the gases between the walls was investigated. The relationship between acoustic impedance, acoustic velocity, and TL was calculated by using the transfer matrix method. The results indicated that characteristics of the internal gases have two effects on TL. One is a change in the double-wall effect, and the other is a change in the reflection coefficient. Gases that have slower acoustic velocities or lower acoustic impedance than air increase the double wall effect. Gases that have faster acoustic velocities increase the reflection oefficient. The calculated results for TL with air, helium, and carbon dioxide agreed well with experimental measurements. Finally, The rating of sound insulation (Rw) defined by JIS A1419-1 (ISO-717) was introduced, and the relationship between Rw and the characteristics of the gases between walls was investigated. The results indicate that gas with a low molecular weight and large ratio of specific heat is more effective to increase the TL.
社団法人日本機械学会の論文
2008-10-25