1980 年 36 巻 4 号 p. 199-209
The effects of wind and temperature profiles on sound propagation are discussed on the base of a generalized wave equation, which is obtained from the fundamental equations of hydrodynamics. It is assumed that the sound source and receiver are both located on a absorptive ground, and that the profile shapes of wind velocity and air temperature are expressed as functions of height only. The approximate solution for the wave equation is found out by the method of smooth perturbation. By considering the contribution of the scattered waves of higher order, an approximate expression for SPL increase on the ground is obtained. The validity of our theoretical discussion is confirmed by the scale model experiments in a wind tunnel, which were carried out by authors as well as by Tachibana et al. . Finally, comparing the experimental data by Tachibana et al. with the results of V. I. Tatarski's theory for the fluctuation of sound pressure amplitude, it is found that takagi's theory explains satisfactorily the amplitude fluctuation characteristics of the sound which propagates leeward.