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.
References
[1]
Van Renterghem, T.; Thomas, P.; Dominguez, F.; Dauwe, S.; Touhafi, A.; Dhoedt, B.; Botteldooren, D. On the ability of consumer electronics microphones for environmental noise monitoring. J. Environ. Monit. 2011, 13, 544–552.
[2]
Smith, D.; Timms, G.; de Souza, P.; D'Este, C. A Bayesian framework for the automated online assessment of sensor data quality. Sensors 2012, 12, 9476–9501.
[3]
Bisdikian, C. On Sensor Sampling and Quality of Information: A Starting Point. Proceedings of the 5th Annual IEEE International Conference on Pervasive Computing and Communications Workshops (PerComW'07), New York, NY, USA, 19–23 March 2007; pp. 279–284.
[4]
Smith, W.L. Self-Testing Sensor. EP 2163905 A1, 17 March 2010.
[5]
Markus, L. Self Testing Sensor. EPO Patent 1666841-A1, 7.
Outdoor Microphone System (Nor1210A and Nor1210C). Technical Report; Norsonic: Lierskogen, Norway, 2009.
[9]
Van Renterghem, T.; Botteldooren, D.; Thomas, P.; Can, A.; Dauwe, S.; Dhoedt, B.; Touhafi, A.; Dominguez, F.; Rademaker, M.; de Baets, B.; et al. Towards an Extensive Noise and Air Quality Measurement Network. Proceedings of the Internoise, Lisbon, Portugal, 13–16 June 2010; pp. 1–6.
[10]
Muller, S.; Massarani, P. Transfer function measurement with sweeps. J. Audio Eng. Soc. 2001.
[11]
Dauwe, S.; van Renterghem, T.; Botteldooren, D.; Dhoedt, B. Multiagent-based data fusion in environmental monitoring networks. Int. J. Distrib. Sens. Netw. 2012, 2012, 1–15.
[12]
Botteldooren, D.; van Renterghem, T.; Oldoni, D.; Samuel, D.; Dekoninck, L.; Thomas, P.; Wei, W.; Boes, M.; ve Coensel, B.; ve Baets, B.; et al. The Internet of Sound Observatories. Proceedings of the Meetings on Acoustics, Montreal, QC, Canada, 2–7 June 2013; pp. 1–7.
[13]
PC Engines. PC Engines ALIX 3d3 Product File, 2013. Available online: http://www.pcengines.ch/alix3d3.htm (accessed on 11 December 2013).
[14]
Marples, D.; Kriens, P. The open services gateway initiative: An introductory overview. IEEE Commun. Mag. 2001, 32, 551–557.
[15]
Soares, Z. Use of Swept Sine in Calibration Services of the Acoustical Metrology Area. Proceedings of the Internoise, Lisbon, Portugal, 13–16 June 2010; pp. 1–10.
[16]
Wright, R.; Goulamhoussen, G. Influences of Weather, Damage and Ageing on the Performance of Outdoor Microphone Windshields. Proceedings of the Internoise, Osaka, Japan, 4–7 September 2011; pp. 1–10.
[17]
Narang, P.; Bell, T. New IEC Standards and Periodic Testing of Sound Level Meters. Proceedings of the Internoise, Shanghai, China, 26–29 October 2008; pp. 1–15.
[18]
Sharma, A.; Golubchik, L.; Govindan, R. On the Prevalence of Sensor Faults in Real-World Deployments. Proceedings of the 4th Annual IEEE Communications Society Conference on Sensor, Mesh and Ad Hoc Communications and Networks, San Diego, CA, USA, 18–21 June 2007; pp. 213–222.
[19]
De Coensel, B.; Boes, M.; Oldoni, D.; Botteldooren, D. Characterizing the Soundscape of Tranquil Urban Spaces. Proceedings of the Meetings on Acoustics, Montreal, QC, Canada, 2–7 June 2013; pp. 1–8.
[20]
Lu, H.; Pan, W.; Lane, N.; Choudhury, T.; Campbell, A. SoundSense: Scalable Sound Sensing for People-Centric Applications on Mobile Phones. Proceedings of the 7th International Conference on Mobile Systems, Applications, and Services, Kraków, Poland, 22–25 June 2009; pp. 165–178.
