Research On Vehicle Interior Sound Quality Based On Noise Active Control Method

Today, the auto industry developing rapidly, the riding quality of the car has already been paid more attention by people. And interior noise offer subjective feelings, it often produces a great influence on purchase tendency of cars. This is the reason why sound quality of vehicle becomes a big concern for carmakers and researcher day by day. On the basis of the project"Analysis and control of car interior noise"and a lot of documents, this paper has proposed a research strategy of using noise active control method to improve the sound quality in the car.First of all, according to the research of the seminar in the past, the paper analyzed and researched the initiative noise reduction method of using engine rotational speed signal as a reference signal to construct initial secondary sound source signal. And based on the above, it improved the noise auto controller (ECU), which has already been developed, changed the error signal amplifier, readjusted the signal and amplify the multiple. At the same time, it also improved the sound power amplifier, made the capability of the controller optimized.Secondly, set up strategies that using active control method to improve sound quality, it has confirmed the advanced FLMS algorithm as the adaptive control algorithm. Inferred the algorithm, discussed the stability and convergence pace of FLMS, it constructed the adaptive model online for LMS algorithm. Through computer emulation analysis, it proved the validity of FLMS algorithm and selected the parameter of FLMS algorithm. According to the received parameter use C language to write FLMS algorithm procedure among Silicon LaboratoriesTDE integrated development environment. Use C language and assembler language to combine and write the control procedure while the procedure writes.Thirdly, this paper made subjective evaluation test on internal noise quality by using two methods of grading and pairing compare, while a certain car is on the operating modes with going at the uniform velocity of different gears location. And calculate the main psychological acoustics parameter that corresponding with each noise sample. Also, set up the regress equation of using objective parameter to describe subjective evaluation result, through linear relevant analysis and pluralism analysis. Result indicates that, while the car is on a steady operating mode, internal noise quality is mainly influenced by two psychological sound parameter-sonority and sharp.Finally, according to the plan that proposed by the paper, we implemented the controlled experiment and analysis, and get a contrast curve of sharp degree and characteristic sonority that before and after control. And also get the effect chart of improved sound quality by active control. Research result indicates that the sound quality agitated degree had reduced about 5 grades after implementing the noise active control. It has proved the feasibility that to control and improve sound quality in cars by adopting the noise active control method.