The distribution of houses plays an important role in the noise propagation in a city area. The tendency of road traffic noise propagation into the city area is made clear by means of scale model and field measurements. In these scale model experiments, an incoherent line source(jet noise type)is used as road traffic noise. Houses are assumed to be only one or two-story houses and are distributed in random order. In this scale model of the residential area, the spatial distribution of sound pressure levels at a specified distance from a road is observed. From the experimental results, we can derive an empirical equation which gives the excess attenuation caused by houses as a correction term. This correction is given as a function of the density of houses, the source height and the distance from the road. Predicted sound level obtained by using the correction term agrees well with the result of the field measurements.