The Study On Testing And Control For Coach Interior Noise

In the globe discussion of environment and resource problem, traffic noise is considered as one of the most important public annoyances. With the development of transportation and standard of living, people's daily life keep closely touch with the vehicle. As a tool riding instead of walk, people's demand of comfort is increasing. In our country, coach manufacturers make great efforts to improve security, high speed, reliability of buses, but the work to improve bus comfort, especially acoustical comfort is very little.The vehicle interior noise includes all kinds of beastly sound inside. The interior noise makes passenger tired, and there is a bad influence on the vehicle comfort. There is a very complex acoustic field in vehicle cavity. It is known, the noise penetrate into the bus interior by two ways: by air and by transmit of vibration on a structure of the vehicle. The vehicle interior noise is mainly caused by irregularity of road, engine and transmission. So ,it is important to study on the regularity of sound transmission in bus cavity and identify the major noise source and investigate the efficient corrective to control noise.This paper reviews the development of vehicle interior noise abatement technology at home abroad, and makes some proposals for the current bus interior noise control in China. And some feasible and effective measures to reduce bus interior noise and the advanced noise control techniques in the developed countries abroad were summarized. Based on a series of signal process and noise source identification techniques, especially the advanced noise source identification method, such as sound intensity analysis, spectrum analysis and vibro-acoustic correlation analysis, the interior noise in three representative coaches, viz. JS6761, JS6985, and JS6770H was studied in detail, the interior acoustical filed characteristic was analyzed, and the primary noise sources and acoustic radiation parts were determined. According to different noise sources, some economical and feasible measures for reducing interior noise and the manufacture of noise reduction prototype vehicle were introduced. The result of noise reduction was excellent. In addition, an experimental investigation on the interior noise of minibus Changan SC6370 was carried out, determining the mechanism of noise generation and transmission and the distributing of interior acoustical field due to engine, transmission and propeller shaft vibration and road irregularity excitation, and the main noise sources were identified.