Monitoring of traffic noise in an urban area using a wireless sensor network

Developments in systems for monitoring environmental noise have made it possible to monitor the acoustic situation within large urban areas. The developments in hardware size and costs, combined with the developments in wireless communication allow to deploy networks with many acoustic sensors without much effort. An application of such a sensor network in an urban environment is discussed in detail. In the application a network consisting of 35 monitoring systems is used to collect acoustic measurements over a 500m by 500m urban area for a period of a week. The measurements are performed to determine local exposure-response relations by comparison of the measured data with results of a local traffic noise annoyance survey, which was organized in parallel. The measurements are also used to improve and demonstrate a model based monitoring approach. This approach combines a detailed model of the area with actual measurements. This combination provides reliable estimates of sound levels as a function of time within the entire area of interest, instead of just at the measurement locations. The advantage of this approach is that it allows to determine the exposure-response relations at locations without a sensor. The setup of the network is discussed in detail with special focus on the required sensor topology, functionality and onboard classification. The results discussed are limited to those related to the acoustic measurements.