TIME VARIABILITY OF URBAN NOISE AND ESTIMATE OF ITS LONG TERM LAeq LEVEL

The proposed European Directive on environmental noise requires that noise descriptors must be determined on annual basis. To reduce the resources for such a long period of monitoring, temporal sampling techniques are usually applied. By this sampling the long term LAeq,LT level is estimated from the LAeq data measured on shorter periods. As the accuracy of the LAeq,LT assessment decreases with the increase of the temporal fluctuation of sound levels and with the reduction of the measurement time, the choice of the most appropriate sampling method is crucial, especially for road traffic noise because this is a typical random phenomenon. The paper deals with the above issue and describes the results of the statistical analyses carried out on an experimental data base, containing the LAeq levels for the day- and night-time periods, measured continuously during the course of one year in 9 sites inside urban areas. The analyses provided useful information on the variability of LAeq levels and the accuracies of the long term LAeq,LT estimated values achievable by three different temporal sampling methods