1980 年 36 巻 4 号 p. 177-184
In a previous paper, a unified procedure of evaluation of noise and vibration control systems has been proposed for the case when random noise and vibration waves of arbitrary distribution type is passed through various type of linear noise and vibration control systems. The validity of this theoretical consideration was experimentally confirmed by applying to only a typically simple noise control system like a single-wall. In this paper, systematical consideration about the insulation properties of general double walls with arbitrary random incident sound waves, which are used very often in the actual engineering field of noise control and its statistical evaluation are given in detail as a typical example of a methodological study on statistical evaluation of noise and vibration control systems. That is, firstly, the impulse and step response properties of general double walls are concretely discussed by developing the theoretical results shown in the previous paper and by using the method of transfer function. Next, a probability density expression of the noise intensity, which is sometimes more important than the instantaneous sound pressure itself in the evaluation and control problems, have been theoretically shown. Experiment was carried out for a double wall composed of two identical aluminum panels which was fixed between two reverberant rooms, using a white noise generator. We can find a good agreement between theoretical and experimental results.