Research On The Objective Evaluation Of Vehicle Sound Quality Of Door-slamming

With the improvement of people’s living standard, the car is not just a means of transport. People pay more and more attention to the ride comfort when they are choosing cars. In recent years, people have found that reducing sound pressure level can not meet market demands. So, sound quality has been highly valued by car companies and it has become a focus in the field of noise control.People’s first impression of a car comes from not only the appearance of the car, but also the sound of door-slamming. The sound of door-slamming could transfer complex information to customers such as comfort, reliability, luxury and so on. Relying on the subjective evaluation, the customers determine the level of automobile, and even decide whether buy the car or not. So, the competitiveness of car companies will be affected directly. Therefore, the research of door-slamming sound is of great importance. Supported by the science fund of State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body (No.60870002), the sound quality objective evaluation of vehicle door-slamming was researched in this thesis.The main research works in this thesis are as follows(1) The door-slamming signals of13passenger vehicles are sampled by utilizing data collected instrument which was manufactured by LMS Company, and the subjective evaluation of the door-slamming sound quality of13passenger vehicles was carried out by using paired comparison method. In order to eliminate the unreliable data, the results of subjective evaluation were examined. Finally, the sound quality subjective performance values of the door-slamming of13passenger vehicles were calculated.(2) The A-weighted pressure levels of door-slamming signals were calculated. The loudness and sharpness were computed respectively by using Matlab program and Test.Lab software. The comparative analysis has been done to verify the accuracy of Matlab program which was worked out by the author, the results show that the Matlab program can be used for the computation of sound quality psychoacoustic parameters of loudness and sharpness. Finally, the sound quality objective evaluation of the door-slamming sound of13passenger vehicles was completed.(3) The parameter of the objective evaluation of door-slamming sound base on Hilbert-Huang transform was developed. The correlation analysis between this parameter and the sound quality subjective performance values has been done. For comparation, the correlation analysis between A-weighted pressure level, loudness, sharpness and the sound quality subjective performance values have also been done. The results show that the new sound metric proposed in this paper has higher correlation coefficient with the sound quality subjective performance values compared with the A-weighted pressure level、loudness、sharpness. So the effectiveness of this parameter was verified.(4) The mathematical model between the subjective evaluation and the objective evaluation parameters of the door-slamming sound was established. Based on the frequency filtering, the main frequency ranges that influenced the vehicle sound quality of door-slamming can be found. Those frequency ranges can be used to guide the design and improvement of the door-slamming sound quality.The subjective evaluation of the door-slamming sound quality of13passenger vehicles was carried out and the objective evaluation parameters of sound quality were calculated. A new parameter SMHHT for the objective evaluation of the door-slamming sound quality based on Hilbert-Huang transform was proposed. Based on the correlation analysis results between subjective evaluation results and objective evaluation results of the door-slamming sound quality, the mathematical model of the objective evaluation of the door-slamming sound quality was established using multiple linear regression. Based on frequency filtering, the main frequency ranges that influence the door-slamming sound quality were identified. The research has a significant practical value in the design and improvement of the door-slamming sound quality.