Investigation of relationships between running speed and sound power levels of vehicles in urban road

摘要

In urban road, the transmission position of vehicles changes frequently due to the transient runningconditions. Therefore, the relationship between the running speed and sound power level ofvehicles is very complex. In this study, in order to investigate these relationships, fieldmeasurements were performed by using three types of vehicles in urban road. From these results,the total running distance was divided into short sections and the average speed and power-meanvalue of sound power levels in each section were calculated. New models for sound power levelswere constructed from these results. As a result, it was found that sound power levels in urban roadwere represented by the formula with term of 9～5 log(V) (V; running speed, km/h) less than 60km/h.