Abstract
A unified statistical treatment of the probability distribution function is theoretically proposed in the case when a general random noise of arbitrary distribution type exhibits various type nonstationary properties due to the temporal change of statistical moments. For the purpose of finding the effect of nonstationarity caused by the temporal change of moments on the resultant probability distribution form, the explicit expression of the probability density function is derived in a general form of statistical expansion series taking the stationary term into the first term of series expansion. Next, a new trial of estimating a noise level distribution over a long time interval on the basis of level distribution within a short time interval is discussed, by using the above theoretical probability expression. The validity of the theoretical result is confirmed experimentally by applying it to the actual level data of the nonstationary road traffic noise observed in a large city.
