A practical prediction method for the stochastic insulation effect of a sound barrier with arbitrary random noise excitation

A sound barrier is often used as a typical noise control device to modify sound propagation characteristics. Also, statistical parameters such as the median value of sound level, $\text{L}{}_{\mathrm{x}}$, as well as the lower order statistical values of sound energy or level, are important for noise evaluation and regulation problems. In this paper, a new trial of statistical prediction for the stochastic insulation effect of a sound barrier is proposed in a special case where the insulation system parameters have to be improved, especially from a methodological viewpoint. Moreover, the improved probability density function (pdf) of output response corresponding to the above parameter change is expressed in the general form of a statistical series expansion taking the original pdf before the system improvement as the first expansion term. The experimental results of applying it in trial to the actual noise data are in good agreement with theory.