Development of a system for continuous environmental noise monitoring (Smolyan, Bulgaria)

Noise pollution is generally regarded as an exposure of people or wildlife to levels of sound that are annoying, stressful, or damaging to the organism. Humans are exposed to noise constantly, from barely audible levels to potentially painful and damaging levels. Cities and agglomerations are subjected to the environmental noise pollution in a greater extent, so the smaller towns and villages are usually neglected in such monitoring studies. The aim of the present study was to: 1) develop a system for continuous environmental noise monitoring; 2) test and validate the system in the urban area of Smolyan town, Bulgaria; 3) assess the level of noise pollution based on systematic measurements. A simple system for continuous environmental noise monitoring has been developed. The system uses budget noise meters, class 2 (verified to be effective enough), placed in special cells for protection from atmospheric influences. The analogue signal from the sound me-ters is digitized and processed by a microcontroller to obtain the equivalent noise levels. This data is transmitted through an Ethernet controller to ThingSpeak, an IoT application and API for storing and retrieving data using HTTP protocols. Data from the continuous monitoring proved the existence of a significant environmental noise pollution in Smolyan (both in the central part and residential areas), which was almost permanent during twenty-four hours and all year round.