Noise Reduction For The Interior Noise And Exterior Noise Of Bus

Domestic and foreign noise rules and regulations, the status of the noise problem, the testing methods and noise controlling strategy are studied in this paper. As for a certain bus, the requirement is determined.Based on the mechanism of the exterior and the interior noise problem as well as the spectral properties of various noise sources, the noise sources, especially in the engine compartment, are identified with hybrid testing techniques, making the work of noise reduction purposive.Initiative and passive means can be used for noise reduction, and the later, especially the sound absorbent and sound insulation are emphasized in the paper. More importantly, absorbent materials are chosen by means of measuring the coefficients with the standing wave pipe. In order to review the functions of absorbent and insulation property of materials, models are built and acoustic results are analyzed with BEM (Boundary Element Method), thus the experiments for evaluating materials are supported.The anticipated effects are achieved through amounts of project practice in noise reduction, and many measures not carried out are also presented. With the governments' increasing stricter command of controlling noise level, the job of noise reduction on buses is unfinished.