1979 年 35 巻 10 号 p. 521-528
In this paper, two basic improvements on the prediction method of road traffic noise have been made for the well-known equally spaced vehicles model in a free sound field. One is based on the standard model of typical city environment with skyscrapers which has an exponential type propagation characteristics of the pseudo-diffuse sound field, since we considered that it is essentially unreasonable to apply the above well-known model in a free sound field to urban road traffic noise. The other is based on a traffic flow model in which a grouping effect of vehicles has been taken into consideration on the standard traffic flow of equally spaced vehicles model, under two typically idealized sound propagation fields corresponding to rural distincts and urban areas. Through the above improvements based on newly introduced ideal models of the sound propagation fields and the grouping pattern in traffic flow, we have been able to get a more precise information on the predicted fluctuation pattern of road traffic noise though it still amounts to no more than a fundamental viewpoint for the actual road traffic noise.