Article

On the ability of consumer electronics microphones for environmental noise monitoring.

Ghent University, Department of Information Technology (INTEC), Gent, Belgium.
Journal of Environmental Monitoring (Impact Factor: 2.09). 12/2010; 13(3):544-52. DOI: 10.1039/c0em00532k
Source: PubMed

ABSTRACT The massive production of microphones for consumer electronics, and the shift from dedicated processing hardware to PC-based systems, opens the way to build affordable, extensive noise measurement networks. Applications include e.g. noise limit and urban soundscape monitoring, and validation of calculated noise maps. Microphones are the critical components of such a network. Therefore, in a first step, some basic characteristics of 8 microphones, distributed over a wide range of price classes, were measured in a standardized way in an anechoic chamber. In a next step, a thorough evaluation was made of the ability of these microphones to be used for environmental noise monitoring. This was done during a continuous, half-year lasting outdoor experiment, characterized by a wide variety of meteorological conditions. While some microphones failed during the course of this test, it was shown that it is possible to identify cheap microphones that highly correlate to the reference microphone during the full test period. When the deviations are expressed in total A-weighted (road traffic) noise levels, values of less than 1 dBA are obtained, in excess to the deviation amongst reference microphones themselves.

0 Bookmarks
 · 
152 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Surveys show that inhabitants of dwellings exposed to high noise levels benefit from having access to a quiet side. However, current practice in noise prediction often underestimates the noise levels at a shielded façade. Multiple reflections between façades in street canyons and inner yards are commonly neglected and façades are approximated as perfectly flat surfaces yielding only specular reflection. In addition, sources at distances much larger than normally taken into account in noise maps might still contribute significantly. Since one of the main reasons for this is computational burden, an efficient engineering model for the diffraction of the sound over the roof tops is proposed, which considers multiple reflections, variation in building height, canyon width, façade roughness and different roof shapes. The model is fitted on an extensive set of full-wave numerical calculations of canyon-to-canyon sound propagation with configurations matching the distribution of streets and building geometries in a typical historically grown European city. This model allows calculating the background noise in the shielded areas of a city, which could then efficiently be used to improve existing noise mapping calculations. The model was validated by comparison to long-term measurements at 9 building façades whereof 3 were at inner yards in the city of Ghent, Belgium. At shielded façades, a strong improvement in prediction accuracy is obtained.
    Acta Acustica united with Acustica 12/2014; 100(6). · 0.71 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To assess the overall noise exposure of the population in Flanders and in particular the exposure to street traffic noise, a measurement campaign was set up involving 250 randomly selected households in Flanders. Measurements were conducted first in 1996 and were repeated twice afterwards. This unique longitudinal noise monitoring exercise revealed that although the traffic intensity has grown over this period, noise exposure on average hardly changed. Small trends in exposure distribution and in statistical noise levels do nevertheless occur but they are marginally significant. Contrasting these measurements with status reporting based on noise maps, prediction of population exposure, and noise annoyance surveys shows that although all of these methodologies have their merits, they cannot be readily compared. In particular the difference between estimated trends in percentage of highly annoyed inhabitants based on noise level measurements and observed trends in reported noise annoyance, is striking.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Several studies show that a significant portion of daily air pollution exposure, in particular black carbon (BC), occurs during transport. In a previous work, a model for the in-traffic exposure of bicyclists to BC was proposed based on spectral evaluation of mobile noise measurements and validated with BC measurements in Ghent, Belgium. In this paper, applicability of this model in a different cultural context with a totally different traffic and mobility situation is presented. In addition, a similar modeling approach is tested for particle number (PN) concentration. Indirectly assessing BC and PN exposure through a model based on noise measurements is advantageous because of the availability of very affordable noise monitoring devices. Our previous work showed that a model including specific spectral components of the noise that relate to engine and rolling emission and basic meteorological data, could be quite accurate. Moreover, including a background concentration adjustment improved the model considerably. To explore whether this model could also be used in a different context, with or without tuning of the model parameters, a study was conducted in Bangalore, India. Noise measurement equipment, data storage, data processing, continent, country, measurement operators, vehicle fleet, driving behavior, biking facilities, background concentration, and meteorology are all very different from the first measurement campaign in Belgium. More than 24 h of combined in-traffic noise, BC, and PN measurements were collected. It was shown that the noise-based BC exposure model gives good predictions in Bangalore and that the same approach is also successful for PN. Cross validation of the model parameters was used to compare factors that impact exposure across study sites. A pooled model (combining the measurements of the two locations) results in a correlation of 0.84 when fitting the total trip exposure in Bangalore. Estimating particulate matter exposure with traffic noise measurements was thus shown to be a valid approach across countries and cultures.
    Environment International. 01/2015; 74:89-98.

Full-text (4 Sources)

Download
199 Downloads
Available from
Jun 5, 2014