title: Active self-testing noise measurement sensors for large-scale environmental sensor networks.
abstract: Large-scale noise pollution sensor networks consist of hundreds of spatially distributed microphones that measure environmental noise. These networks provide historical and real-time environmental data to citizens and decision makers and are therefore a key technology to steer environmental policy. However, the high cost of certified environmental microphone sensors render large-scale environmental networks prohibitively expensive. Several environmental network projects have started using off-the-shelf low-cost microphone sensors to reduce their costs, but these sensors have higher failure rates and produce lower quality data. To offset this disadvantage, we developed a low-cost noise sensor that actively checks its condition and indirectly the integrity of the data it produces. The main design concept is to embed a 13 mm speaker in the noise sensor casing and, by regularly scheduling a frequency sweep, estimate the evolution of the microphone's frequency response over time. This paper presents our noise sensor's hardware and software design together with the results of a test deployment in a large-scale environmental network in Belgium. Our middle-range-value sensor (around €50) effectively detected all experienced malfunctions, in laboratory tests and outdoor deployments, with a few false positives. Future improvements could further lower the cost of our sensor below €10.
authors.affiliation: Department of Electronics and Informatics (ETRO), Vrije Universiteit Brussel, Pleinlaan 2, Elsene 1050, Belgium. federico.dominguez@vub.ac.be.
authors.forename: Federico
authors.initials: F
authors.lastname: Domínguez
authors.forename: Nguyen The
authors.initials: NT
authors.lastname: Cuong
authors.forename: Felipe
authors.initials: F
authors.lastname: Reinoso
authors.forename: Abdellah
authors.initials: A
authors.lastname: Touhafi
authors.forename: Kris
authors.initials: K
authors.lastname: Steenhaut