ON THE USE OF THE SOUND INTENSITY METHOD FOR DETECTING NOISE SOURCES NEAR THE REFLECTING PLANES

摘要

The problems in the identification and localization of noise sources using the sound intensity method are dealt with for the reactive field. For these purposes, a three dimensional model structure resembling the engine room of the passenger car is considered. The model contains complicated noise sources distributed within the small space, which includes the narrow, connected, reflecting planes constructed with rigid boxes. In addition, a small clearance exists between the structure and the reflecting bottom. The sources are actually hanging in the space over this rigid bottom. For this model, the near field acoustic intensity is calculated scanning over the upper plane opposite to the bottom by using the acoustic boundary element method. The effects of relative source phases, frequencies, and locations are investigated. It is observed that the application of sound intensity method without proper care in this situation can yield the detection of fake sources. Therefore, the sound intensity scanning over the engine room upper, with its hood open, may indicate the false positions or components as noise sources. The field reactivity has to be checked and the care should be attended in this type of measurement using the sound intensity methods.