| Nowadays, traffic noise is being overwhelmingly regarded as one public environmental pollution, since vehicles are popularized worldwidely as a common traffic and transportation tool. However, the higher requirments are demanded in the following aspects like reliable safety, high speed and confort as well. Generally, cars made in China can reach these requirements. But, there is little work being conducted on reducing the noise so far. This dissertation presents and discusses the following contents: Generating mechanism, and measuring & analyzing method of noise; Generating sources, frequency characteristics, and common controlling measures of traffic noise. According to the sound-absorbing principle of porous material, a new kind of rice-straw composites (RSC) has been studied and applied in sound-absorption, manufacturing process, and properties of laminated rice-straw composites (LRSC) .RSC at various densities had a sound-absorption coefficient of 0.5 to 0.9 as to sound frequency of 1000 to 2000Hz due to the quantity pores in and between rice straws at a low compression. Theoretically, porous struction of rice straw composites can lead to resonance if sound frequency equals that of rice-straw composites, which consume acoustic energy. Accornding to the theory of sound insulation, each layer materials and parameters can be detemined. XMQ6608 vehicle generator hood is made of LRSC and boasts 16 percent higher than current hoods in noise insulating value.
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