Insulating buildings against transportation noise

Transportation noise contains significant low frequency components. It is difficult to sound insulate buildings against transportation noise because wall cavities are only effective in increasing sound insulation above the mass-air-mass resonance frequency. Stud walls can also have a significant structural resonance in this low frequency range, although it is not yet clear if this is significant in the field. This paper gives typical diesel electric locomotive traffic noise, road traffic noise, aircraft traffic noise and other rail traffic noise spectra. The paper examines the sound insulation of measured wall sound insulation spectra against these typical transportation noise spectra using A-weighted sound level reduction. This will be compared to the Rw + Ctr and Rw values of the walls. Another problem with low frequency sound insulation is the large uncertainty in both laboratory and field measurements. The adoption of Rw + Ctr in the Building Code of Australia will make the common single number rating more appropriate for transportation noise