Study On The Methods And Application Of Objective And Subjective Evaluation For Passenger Car Door Closing Sound Quality

With the rapid development of the automotive industry and the continuous improvement of people's living standards,the people's comfort requirements of the car increase.The noise,which is regarded as one of the main factors in the quality evaluation of the car,is becoming increasingly noticeable.Therefore,the researches and applications of Sound Quality has been drawing attention from various car manufacturers in recent years,as the traditional noise control measures are limited in improving the comfort feeling.As an important aspect of the customer-perceived car quality,Sound Quality has become a key factor influencing the product competitiveness.Specially,its sound quality of door-closing noise is of great importance.If the door-closing sound quality of car is poor,the customers will be upset.Therefore,the cars' door-closing sound quality research is already an important part of the automobile sound quality research.Aiming at improving the overall automobile sound quality,this thesis studied the door-closing sound characteristics of a particular car using a hybrid method combining a subjective-parameter calculation and an objective-evaluation experiment,based on which the subjective preference model was derived.The main contents include:(1)Subjective and objective evaluation of the door-closing noiseFirstly,different subjective evaluation methods are introduced.The properly-designed subjective evaluation tests are implemented on 12 different passenger vehicles using the equally-spaced single-scale grading method and reliable results are obtained after careful data processes.Then,the traditional psychological sound factors,such as loudness and sharpness,are calculated and the results prove that the sharpness overflow is in strong correlation with the subjective preference.Finally,the subjective preference model is established using a multiple linear regression process between subjective and objective evaluations.(2)Theoretical analysis for the sample signals of the door-closing soundThe acoustical characteristics affecting the door-closing sound are investigated by applying time-frequency analysis and frequency-filtering techniques on the sample noise signals and the effective frequency range is thus determined using different filtering methods,which provides a theoretical basis for the door-closing structure optimization.(3)Structure optimization aiming at enhancing the door-closing sound quality Various structural factors influencing the door-closing sound quality are studied,among which the stiffness of the side latch panel is found to be of great importance.Therefore,the structures of the rear door,side panels and latch are optimized and the feasibility of the optimization is proved by an obvious improvement in the subjective preference.