Personal noise ranking of road traffic: Subjective estimation versus physiological parameters under laboratory conditions

Abstract

Objective To evaluate the subjective estimation of noise-induced discomfort and its correlation to psychoacoustic and physiological parameters under laboratory conditions. To establish an effective description of sound qualities of road traffic noise, supplementing the current standards and calculation specifications. Methods Pass-by vehicle noise samples were binaurally recorded with a dummy head measurement system, and synthetically composed to six vehicle ensembles considering different road beds, varying speed profiles and noise barriers. Fifty-one persons were selected and tested under laboratory conditions. Study participants were exposed to defined acoustic stimuli, alternating with neutral phases lacking acoustic content in a listening room. Concomitant recording of electrocardiogram (ECG) and respiratory rate was performed. Subjective estimation of noise-induced discomfort of assigned vehicle ensembles was rated on a personal ranking scale (PRS) by the study subjects. Subjective ratings were combined with objective psychoacoustic parameters by multiple regression analysis. Results Heart rate was increased during all noise exposure phases compared to neutral phases; the increase of heart rate differed among vehicle ensembles and was statistically significant in two cases ( p<0.01). Respiratory rate remained unaffected. Personal rankings also differed among vehicle ensembles and correlated well with objective psychoacoustic parameters ( p<0.0001); e.g., loudness combined with roughness describes the correlation with subjective estimation of noise-induced discomfort better than the A-weighted sound level. Vehicle ensembles rated more unpleasant caused higher increases in heart rate as well ( p<0.0001). Conclusions The sound quality of road traffic noise as it is described by various psychoacoustic parameters not only determines the subjective estimation of noise-induced discomfort but in addition affects physiological parameters like heart rate. This should be considered for future perspectives in road- and traffic planning and therefore may serve construction engineers as well as traffic planner as a supplemental tool.