Selective monitoring of noise emitted by vehicles involved in road traffic

Abstract

An acoustic intensity probe was developed measures the sound intensity in three orthogonal directions, making possible to calculate the azimuth and elevation angles, describing the sound source position. The acoustic sensor is made in the form of a cube with a side of 10 mm, on the inner surfaces of which the digital MEMS microphones are mounted. The algorithm works in two stages. The first stage is based on the analysis of sound intensity signals, and it detects acoustic events. The second stage analyses a detection function based on the normalized source position; its task is to determine whether the acoustic event represents a vehicle passing the sensor and detecting its movement direction. The acoustic probes were mounted inside intelligent lamps that illuminate the roadways depending on the volume of traffic. The paper explains how accurately traffic can be monitored through directional noise analysis and shows the resulting application to smart cities. [The project has been subsidized by the Polish National Centre for Research and Development (NCBR) from the European Regional Development Fund No. POIR.04.01.04/2019 entitled: INFOLIGHT—“Cloud-based lighting system for smart cities.”]