| Vehicle noise level is one of the most important factors in the evaluation of vehicle quality.The power-based noise reduction(PBNR)testing method is the cornerstone of the research in the area of vehicle noise reduction.However,the poor repeatability and stability of testing results between laboratories indicate that the method doesn't have a standard and norm.This paper focus on the optimization of the PBNR testing method,in order to get an efficient and accurate testing method.The research includes the following four aspects: the algorithm,source setup optimization,receiver setup optimization,other background noise settings.The results show that,(1)the sound pressure level to sound pressure level algorithm is most suitable for PBNR test;(2)the optimal set for calibration test of sound source is: a tube microphone with a distance of 10 mm from the tube mouth plane and four response microphones;(3)use 1/2 inch microphone which dynamic range covers up to 16 d B(A),and try to point to the direction of sound source incidence to arrange the response microphone;(4)the number of microphones in each path is 6 at the floor of the vehicle,4 on the left front tire,4 on the right rear tire,18 on the engine compartment,2 on exhaust,4 on the each side waist line outside the vehicle.(5)background noise should be controlled within 8d B(A)at 1/3 octave point above 400 Hz.After optimization,the method studied in this paper can control the laboratory calibration error within 1d B,and through the optimization of engine compartment and vehicle floor path PBNR,the vehicle can achieve the PBNR target value.The specification can help the industry to quickly establish and share a basic database.The research results in this paper are based on pure fuel vehicles,and there are still some limitations and deficiencies.Other researchers can carry out further studies on electric vehicles,other transmission routes,as well as the reduction of off-vehicle noise. |
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