The influence of binaural effects on annoyance for transportation noise

A laboratory study was conducted to identify the significance of the binaural effect on annoyance by transportation noise. There were 377 participants (240 male and 137 female). Every participant marked the annoyance score (from 0 to 10) for each stimulus on their questionnaire. All of data were divided into four groups according to four types of transportation noise sources. The difference in the mean annoyance scores between subgroups according to sound recording/playback techniques was statistically significant in the four noise groups. Stepwise multiple regression analysis was conducted. Using a regression model, predictions of L_Aeq, Technique and their interaction term (L_Aeq^* ) involving dummy variable were made. In spite of some limitations of the process of the laboratory test, meaningful results were acquired. This study showed that the binaural effect was one of the acoustical factors modifying annoyance, and quantitative expression of binaural effect is suggested. Annoyance was explained by L_Aeq and an interaction term in the resultant model functions for the four noise sources. Regression coefficients of the interaction term for each model equation were almost the same, which explained the extent of the binaural effect. The binaural effect was defined as the difference of annoyance variations between two sub-groups when L_Aeq varies by ΔL_Aeq from the specified noise level. The binaural effect was expressed as 0.01ΔL_Aeq on the basis of a 0 to 10 annoyance scale.