Estimation Method for Vehicle Aerodynamic Noise Considering Near and Far Acoustic Fields

An estimation method for vehicle aerodynamic noise considering characteristics of acoustic near field and far field is suggested. The wave length of low frequency sound is so long that local pressure fluctuations called pseudo-sound are predominant over acoustic waves. Low frequency aerodynamic noise inside the cabin is affected by pseudo-sound on a vehicle body surface. Wave length of high frequency sound is shorter than that of low frequency. Pseudo-sound attenuates and vehicle body surface is excited by not only it but also by acoustic waves. 車室内空力騒音へ影響する物理量として，気流の対流による変動レベルの大きい圧力変動だけでなく，音波の圧力変動も考慮する必要があると考えられた．特に高周波数帯域では，音波の圧力変動が支配的にサイドガラス面上に分布している領域が存在し，その領域では質量則に基づいた音響透過損失に従っていることが確認された．