A new algorithm to monitor noise pollution adapted to resource-constrained devices

European Directive 2002/49/EC indicates that member states must provide mappings of noise levels throughout all areas with more than 250,000 inhabitants and for all major roads with a traffic volume exceeding six million vehicles per year. Noise levels in regions containing major railways and airports should be mapped as well. Traditionally, noise mappings have been created using sound level meters, and the noise indicator used is the equivalent continuous sound pressure level. However, over the last few years, Wireless Sensor Networks have been proposed for this task, but little attention has been paid to the deployment of frequency-based algorithms adapted to resource-constrained devices to calculate the noise indicator. This work presents a new algorithm based on frequency domain, which has been implemented successfully in a resource-constrained device for calculating the noise indicator. Several experiments have been carried-out using a variety of scenarios to compare the differences between the noise indicators calculated by the sensor and those from a commercial sound level meter. The results show the effectiveness of the algorithm because the difference between our method and the traditional technique is less than 2 % (1.2 dBA). This comparison pertains to an urban area, and it demonstrates that the proposed approach can be used for noise mappings in real time and space.