What annoyed me – vibration or low-frequency noise?

It has been identified by the Western Australian Department of Environment and Conservation (DEC) that many complaints regarding vibration problems are actually noise problems. The DEC recently received a complaint about railway operations from a resident in the Perth suburb of Canning Vale. The complainant targeted vibration as the problem, indicating that the whole house was vibrating when the freight train passed by. Investigations conducted by the DEC indicated that while the vibration level inside the house was significantly elevated when there was a train passing-by, the levels were not high enough to cause a problem, as they were all far below Curve 1 specified by AS2670.2-1990. The A-weighted noise level inside the house, though also elevated during the train operation, was also below a level that normally attracts complaint. Further analysis of the measured data indicated that lowfrequency noise might be the major issue. Very strong low frequency noise energy in the range from 12-32 Hz was recorded inside and outside the house. However, because the building structure is more efficient in attenuating the high-frequency noise, the low-frequency energy becomes more obvious inside the house. The difference between C and A-weighted noise levels increased from 20 dB outside the house to more than 30 dB inside the house. The analysis identified that the size and shape of a room might also contribute to the higher level of low-frequency noise inside that room. This study also indicated that there is the possibility that the low frequency noise may be due to regenerated noise from ground vibration.