Acoustical indicator of noise annoyance due to tramway in in-curve operating configurations

Abstract

Tramway gives rise to annoyance. Particularly, tramway in an in-curve operating configuration often emits squeal noises leading to inhabitants’ complaints. Noise exposure levels were not sufficient to account for annoyance. Other acoustical factors could explain noise annoyance. A laboratory experiment is carried out in order to identify and characterize the influential acoustical factors of in-curve tramway noises. Subjects are asked to rate the short-term annoyance caused by 14 tramway pass-by noises, recorded in situ for various in-curve operating configurations. A psychoacoustical analysis shows that the overall perceived noise level, the irregular character and the treble character of tramway noises influence noise annoyance. These acoustical features are taken into account through the following indices: the mean loudness, the variance of time-varying A-weighted pressure normalized by RMS A-weighted pressure, and a psychoacoustical index, constructed to account for squeal noise, expressed by the total energy of the tonal components within critical bands from 12 to 24 Barks. A multilevel regression analysis reveals that a combination of these indices proves to be satisfactory for predicting short-term annoyance due to in-curve tramway noises. These results are consistent with those from a previous experiment that implied 61 tramway pass-by noises corresponding to different operating situations.