1980 年 36 巻 7 号 p. 357-365
Statistical energy analysis is used to predict the internal sound pressure and the external of a rectangular enclosure with five flexible panels except a base pane, such as the acoustical enclosure, when the enclosure is excited by the structure-borne sound. The spatial average of the time-mean-square velocity measured on five panels is used to obtain those sound pressures. It is shown that the external sound pressure near the panel can be computed as the sum of the sound radiation power due to the flexural vibration and the non-resonant sound transmission power of the panel, if the receiving room is assumed to be the free space or the anechoic room. The noise reduction produced by a rectangular enclosure can be obtained from the ratio of the internal sound pressure to the external. The ratio of the non-resonant sound transmission power from the test panel to the sound radiation power from the same area of the infinite rigid panel (such as the piston) having the same velocity with the panel is computed, and the apparent sound radiation efficiency, that is, the sum of the sound radiation efficiency and this ratio is introduced. For the noise reduction and the apparent radiation efficiency, experimental results are compared with theoretical predictions with generally good agreement.