抄録
Acoustic pollutions are now as important social problems as air and water pollutions. In our social life various complex sound fields due to acoustic sources of more or less random nature are produced. Therefore, in this paper, these noise sources are characterized by stochastic time functions and the propagation of noise radiated by them is considered by using correlation analysis. At first radiated sound fields due to stationary or nonstationary random point source, fixed in space, are considered. Power spectrum, mean square average and correlation funcutions of the fields are expressed in terms of the corresponding quantities of the source and transfer functions. Then, we discussed the sound field radiated by a random point source moving at a constant velocity which simulates a car, an aircraft etc. Both subsonic and supersonic cases are considered. Next we studied a sound field radiated by a flow of random point sources simulating a road traffic. The mean square values of the field is expressed as a function of now density, velocity and power of each point source as well as distance from observation point to the flow. The above considerations may give some basic informations on propagation of noise and be useful to establish a criterion for noises.
