A new on-line estimation method of representative statistics of environmental random noise and vibration based on actual digital measurement.

Abstract

It is obvious that a strictly stationary random process seldom exists in the practical random phenomena such as urban noise and vibration. In the actual observation of random noise and Vibration environment, it occurs very often that the level data of random noise and vibration are sampled in the digital form at discrete time intervals by use of a sound level meter and vibration meter. Hereupon, the use of digital computer is essential for various types of statistical evaluation(e. g. , median, mean value, variance, L_x, etc. )on the above random noise and vibration data. From these practical points of view, a unified expression of random noise and vibration level distribution which is applicable to arbitrary types of distribution form and nonstationary characteristics is newly established in this paper. More concretely, the explicit expression of probability function for randam noise and vibration level fluctuation is derived in the general form of statistical orthogonal expansion series. Next, based on the above unified expression, a new algorithm estimating the representative statistics such as L_x level is theoretically proposed, in the sequential form of on-line treatment. Finally, the actual effectiveness of the proposed on-line estimation method is experimentally confirmed by applying it to the experimentally observed road traffic noise data in the city.