![Fire truck driving by a crowd of people blocking their ears on the sidewalk](/sites/g/files/omnuum10826/files/styles/hwp_21_9__1920x825/public/datasmart/files/christian-lendl-jis3g8opwca-unsplash_01.jpg?itok=qCi9PeW2) # Map Monday: Noisy City **Noise Pollution and Data Sonification** January 09, 2023 [ Betsy Gardner ](/betsy-gardner) --- **Map**: [Noisy City](https://noisy-city.jetpack.ai/) **Geographic Area:** Brussels, Belgium **Year Published:** 2020 **Goal:** Visually and auditorally display noise pollution in Brussels. **Datasets:** Data came from sensor networks in the city. --- *Complementing* [*Harvard’s Map of the Month*](/map-month "Map of the Month") *series, Map Monday highlights a data visualization that enhances understanding of or helps resolve a critical civic issue.* Sirens. Motorcycles. Car alarms. Dogs barking. Car horns. Skateboards. Children playing. Airplanes overhead. While these are often considered nuisances that one must put up with when living in an urban area, these sounds are also main sources of noise pollution and, over time, can cause serious damage. The contamination that we can identify visually, like billowing smoke stacks belching out black smog or trash being littered across a park, are easy to understand as pollution. Auditory pollution might not be as easy to track, but it’s important to understand where and how it occurs and what can be done to mitigate it. Erica Walker, an assistant professor of epidemiology at Brown University’s School of Public Health and a community activist, has spent more than a decade researching the relationship between community health and noise. The founder of the [Community Noise Lab](https://communitynoiselab.org/), Walker initially became interested in how people experience intrusive noise when living below loud neighbors; after realizing that there was very little research into the impact of noise pollution, she began studying the relationships between traffic noise and cardiovascular health. Since then, her work has been published in several journals and she has received public health grants to continue researching noise pollution. Currently, her work is looking at the intersection of noise pollution, environmental justice, and physical health outcomes in the New England region and the state of Mississippi. In 2018, the World Health Organization noted that “prolonged exposure to environmental noise is associated with [increased risk to both physiological and psychological health](https://www.frontiersin.org/articles/10.3389/frsc.2021.768227/full#main-content)” including higher rates of hypertension, coronary heart disease, and stroke. However, mechanisms for measuring and even visualizing noise pollution are rare, although there are [smartphone apps, like Walker’s NoiseScore](https://communitynoiselab.org/noisescore/), that allow citizen-scientists to measure and/or describe the noise around them. In 2020, data scientist Karim Douïeb compiled[ noise pollution sensor data from Bruxelles Environnement](https://environnement.brussels/thematiques/bruit/donnees-bruit/mesures-de-bruit), the administration for the environment and energy in the Brussels-Capital Region, into an [interactive, audio heat-map of Brussels called Noisy City](https://noisy-city.jetpack.ai/). ![Screenshot of the Noisy City map ](/sites/g/files/omnuum10826/files/2025-05/unnamed%20%2813%29.png) While the map uses color coding to show annual average noise intensity (AANI) in decibels with deep blue, purple, and gray sections being the loudest, the map also has an audio component. Hovering the cursor over different sections of the city not only highlights the color and moves the dial up in decibel intensity, it also plays the sounds at the volume being experienced by people on the ground. One of the noisiest areas is the municipality of Haren, located in the upper north-east corner of the city, which can have an AANI from 60dB to more than 75dB. Once an automobile manufacturing hub, the area still has huge train yards with multiple active tracks and stations, and is next door to the city’s airport. This reflects the intensity of what the Bruxelles Environnement calls [structural noise](https://environnement.brussels/thematiques/bruit/les-sources-de-bruit), or noise “related to road traffic (cars, trucks, motorbikes, buses, trams, metro and even waste collection and road cleaning), rail traffic and air traffic.” This area of the city has high exposure to those structural sounds. In contrast is the pastoral neighborhood of Vogelzang, which has an AANI of less than 45dB and is color-coded green on the map. This is an example of [situational noise](https://environnement.brussels/thematiques/bruit/les-sources-de-bruit), which is noise from things like air conditioners, leaf blowers, local restaurants, playgrounds, dogs or other pets, music, and local roads. Interestingly, Bruxelles Environnement reports “[the greatest number of complaints](https://environnement.brussels/thematiques/bruit/les-sources-de-bruit/bruit-des-installations-classees)” are about noises from the hospitality/catering sector, private home occupants or equipment, and retail shops which are situational. ![Zoomed in Noisy City map showing quieter area with low decibel level](/sites/g/files/omnuum10826/files/2025-05/unnamed%20%2814%29.png) This map was so popular that Douïeb was asked to create [noise pollution heat maps for Paris, New York City, and London](https://interactive.wearepossible.org/noisycities/#/?city=paris&language=en). Each city map includes its respective data sources including the [“innovative urban noise monitoring network” RUMEUR in Paris](https://www.conforg.fr/euronoise2015/proceedings/data/articles/000043.pdf) and the [US DOT National Transportation Noise map](https://maps.dot.gov/BTS/NationalTransportationNoiseMap/) for NYC. In a 2022 interview with Claire Santoro of the Data Visualization Society, Douïeb described the technical process, which includes building out the maps in open-source geographic information system (GIS) software and then loading them into Mapbox. The “data sonification” aspect “comes from a looping mp3 mixing various city sound recordings” which is volume controlled based on where the user hovers over the map. These maps and other methods for tracking and displaying noise pollution are gaining popularity, as awareness grows around the damage it can cause. In 2019 the local Brussels-Capital Region government adopted the [Quiet.Brussels Plan](http://document.environnement.brussels/opac_css/elecfile/PROG_20190228_QuietBrussels_FR.pdf) and one of its main objectives is reducing the negative effects of noise on residents' health. The city’s [broad, environmental-noise sensor network](https://www.mdpi.com/1424-8220/13/12/17241/htm) that informs the Noisy City map is also being used to monitor progress on the Quiet.Brussels goals. Thanks to Douïeb’s efforts, the public will be able to see — and hear — if the city is on track. ## About the Author ### Betsy Gardner ![Headshot of Betsy Gardner](/sites/g/files/omnuum10826/files/styles/hwp_1_1__100x100_scale/public/2025-05/Betsy%20Headshot%20resize.jpg?itok=k2OsSp1g) Betsy Gardner is the editor of Data-Smart City Solutions and the producer of the Data-Smart City Pod. Prior to this, Betsy worked in a variety of roles in higher education, focusing on deconstructing racial and gender inequality through research, writing, and facilitation. She also researched government spending and transparency at the Lincoln Institute of Land Policy. Betsy holds a master’s degree in Urban and Regional Policy from Northeastern University, a bachelor’s degree in Art History from Boston University, and a graduate certificate in Digital Storytelling from the Harvard Extension School. See also:- [ Data Visualization ](/topics/data-visualization) - [ Public Health ](/topics/public-health) Share on:- [ Facebook ](#) - [ Twitter ](#) - [ Linkedin ](#)