Three models are relevant in evaluating socio-economic cost of traffic noise: a noise pricing model which formulates a yearly socio-economic cost for each dB reduction, an acoustical model which determines traffic noise levels in the front of each house, and a distribution model which specifies the number of inhabitants for each dB interval. For a given distance and a receiver height, sound propagation attenuation varies in a certain extent depending on distance, due to variations in shielding effect, in local ground elevation/attenuation, etc. Accordingly, such sound propagation attenuation shall, as proposed in this work, be described in two parts: a representative sound attenuation pattern and a scattering distribution function. The studied example is a noise mapping result for a housing area of about 3100 dwellings. Based on the noise mapping data, a distance-dependent standard deviation function was worked out. Together with the use of the Gaussian distribution, this distribution function can, as believed, describe the scattering feature. In Sweden, four typical sound attenuation patterns have officially been accepted. Expected, representative standard deviation patterns will also be worked out in near future. Then, a quick estimation of the socio-economic cost, independent of costly noise mappings, will become possible.