HUMAN RESPONSE TO STRUCTURALLY RADIATED NOISE DUE TO UNDERGROUND RAILWAY OPERATIONS

Abstract With growing demand for public transportation, new railway lines are being built in tunnels in urban areas. The vibration generated by the trains can propagate into the structure of buildings close to the tunnels, where it can be radiated as noise in the building interior. This noise can usually be heard as low frequency “rumble”. Analysis of the noise in dwellings near underground railway tunnels confirmed that the noise comprises frequencies from about 20 Hz to 200 Hz with either one or two broad peaks. The noise was simulated in a laboratory study to investigate human response to the noise and the effect of background noise level. Two types of specific noise with either a 50 Hz or 80 Hz broad peak at seven levels between 50 and 78 dB (Lin), and two background noise levels of 55 and 65 dB(Lin) were used in the study. The study confirmed that annoyance is related to the level and frequency spectrum of the specific noise level; the specific noise with the 80 Hz peak is more annoying than the noise with the 50 Hz peak; the same level of specific noise with low background noise is more annoying than it is with high background noise. Relationships between the annoyance and noise levels in terms of linear or A-weighted sound pressure level, linear or A-weighted level difference between noise and background, and level above threshold of audibility were evaluated. The A-weighted sound pressure level was found to be adequate for predicting both individual and mean annoyance of the specific noise. The results also showed that the hypothesis suggested by the Acoustic Feature Model regarding the relationship between annoyance and sensory magnitude of a noise feature is valid for the specific noise.