Measurement and Analysis of Automobile Wind Noise

The transmission of aerodynamically-generated noise through panels in automobiles has become of more pressing interest in recent years. As automobile engines, transmissions, and tires have become quieter, wind noise has become more noticeable, particularly at higher speeds. Hence, an automobile manufacturer would like to know how to design the automobile to minimize the wind noise levels heard by the passengers. In this investigation, both experimental and analytical methods were applied to the problem. A simplified model of an automobile side window was subjected to wind tunnel tests. The effects of window thickness and edge conditions on the transmitted wind noise level were investigated. An attempt was made to analytically predict the transmitted noise level by using a simple Statistical Energy Analysis (SEA) model, which used an empirical expression for the fluctuating wall pressure on the window of an automobile. The measurements showed that the plate thicknesses and edge conditions studied had only small effects on the level of transmitted noise. The analytical prediction method looked promising. The method was successful at predicting the frequency distribution of transmitted noise very closely, and it predicted the absolute levels to within 10 dB.