The discomfort model of the micro commercial vehicles interior noise based on the sound quality analyses

Abstract

The micro commercial vehicles are very popular in the developing areas of China for its capability of loading both cargoes and people. With the demands of customers for improving the comfort of vehicles, it is necessary to develop a discomfort model of noise for the micro commercial vehicles based on the acoustical characteristics of the interior noise, which are different from other passenger cars when they are running in various road conditions. This study investigated the discomfort produced by noise of 3 models of micro commercial vehicles when they are running in 4 types of road conditions, i.e., the asphalt, concrete, gravel and bump road. Seventy-four noise stimuli with the sound pressure levels (SPLs) ranging from 52 to 70 dB(A) were regenerated based on the recorded noise samples for the subjective evaluation experiment. Thirty subjects judged the subjective discomfort of the noise stimuli using the absolute magnitude estimation (AME) method. The relation between the subjective magnitudes of discomfort and the acoustical parameters (i.e., the loudness, sharpness, roughness and articulation index) was analyzed. A tentative equation was obtained by multiple linear regression analysis to predict the discomfort caused by noise of the micro commercial vehicles. The partial correlation analysis was applied to determine the contribution of each psycho-acoustical parameter on discomfort. The results showed that the loudness and sharpness were the influential factors of the discomfort. The subjective magnitudes of discomfort were also transformed into the ratings scales, which were usually employed by car companies.