Research On Quality Analysis Of Vehicle Interior Noise And Selective Noise Control Method

In the rapid development of automobile industry today, interior noise has become animportant evaluation index of ride comfort and product quality, it is good or bad will have agreat influence for the purchase intention of consumers and market competitiveness of theproduct. In the past the regulations and standards of car noise, mostly in A weighted soundlevel as noise evaluation, However, A level no in-depth consideration of vehicle interiornoise acoustic quality characteristics, not a comprehensive response to noise feeling.However, A-weighted sound level without deep considerations of the quality characteristicsof interior noise sound can not fully reflect the feelings of noise. In this case, the newconcept of modern noise-sound quality emerge as the times require, and it points out thatnoise of people’s feel is affected by the psychological and physiological factors, reflected asthe subjects of evaluation on certain conditions the subjective perception of sound.By using both passive and active control method can effectively control the interiornoise of vehicle sound quality. The traditional passive noise method can be in a widefrequency range for medium and high frequency noise reduction, but the low frequencynoise suppression effect is weak, and it is difficult for interior sound quality to be improved.The method of active noise reduction to make the noise control is more targeted, can beachieved interior noise frequency segments are selectively cancel, used to achieve thepurpose of improving sound quality inside vehicle, and the low frequency noise controleffect is good.Based on the National Natural Science Fund Project “the car interior noise qualityanalysis and method research of adaptive active control ", car interior noise sound qualityanalysis and control strategy as the main lines, preference and annoyance as an index to China’s domestic car interior noise of subjective evaluation and objective quantitativeanalysis. By means of digital filtering techniques were noise selectively active noise controltheory and method research,, developed the active noise control in vehicle principleprototype, constructed inside the adaptive active noise control system, and in some types ofChina-made cars was carried out on the car interior noise selectively active controlexperiment and the noise quality were analyzed. The paper mainly completed the followingresearch work:First, collect eight different types of domestic car in the uniform steady state drivingand the driving cycles of a uniformly accelerating car sound samples as evaluation object,29men formed the evaluation team, adopts adaptive grouped pair-wise comparison methodOn the subjective evaluation of the test data has been rigorously tested, and weed out theevaluation result was out of the ordinary evaluation, finally obtained the sound samplesound quality preference performance value and annoyance rating value in differentconditions; and the subjective evaluation results and five psychoacoustic parameters andtwo kinds of A-weighted sound pressure level carried out correlation analysis and multiplelinear regression analysis. The results show that the loudness and sharpness of interiorsound quality are more significant effect in steady state conditions; and when the loudnessis more suitable as vehicle is describing the good-bad index of interior sound quality inuniformly accelerated conditions.Secondly, by means of selective subtraction of vehicle interior noise componentthat the sound quality is greatly influenced by the band amplitude method, adjustment andimprovement of interior noise quality characteristics。Adaptive control method is proposedbased on frequency selective filtering of NFSFLMS algorithm，study on the controlmechanism of selective noise elimination for adaptive active control system in vehicleinterior noise; The simulation model constructed of algorithm in Matlab/Simulink andrational setup of filter’s parameters, single frequency noise signal and narrowbandrandom signal noise signal carry out the simulation analysis of adaptive elimination, theresults proved that the algorithm is efficient.Again, based on the above theory, the selective adaptive active control system of vehicle interior noise is designed and developed. The hardware of the system consisting byprogrammable preamplifier module and signal adjusting module、 programmablepreamplifier module、 programmable preamplifier module、plastic module of speedsignal、A/D conversion module、main controller、D/A conversion module、programmingand communication interface、sound power amplifier module and the power supply modulecomposed the hardware of an adaptive active controller. The control system isprogrammed by C language and assembly language mixed programming method in SiliconLaboratories IDE of the development environment, which includes the initializationprocedure, module call procedures, adaptive algorithm and selective program of digitalfiltering. Finally, based on adaptive active control system of interior noise of thefrequency selective filter, hardware design and software development work havecompleted.Finally, that was independently developed the controller as the core, adaptive activenoise control system of interior sound quality was constructed in a certain domestic car. Insteady-state conditions, using the NFSFLMS algorithm was implementing selective activecontrol for noise of the occupant ears. The results show that, the noise of cancellationfrequency decreases obviously, other frequency components are almost uninfluenced; theloudness and sharpness value has been effectively reduced; the SQ value of evaluationindex will increase14%above for interior sound quality。In the acceleration runningcondition, the noise near the driver’s ears was made active control by the FXLMS algorithm.The results showed the energy of noise and amplitude was decreased, acceleration ofinterior sound quality is affected, which the loudness has fallen by nearly10%, theevaluation index-SQ value of sound quality increased by16%.