Those vacation photos you view with envy on social media typically capture what a city looks like. But with a bit of research and an algorithm, they can also reveal a city’s soundscape.
And that information says a lot about how people perceive a city or neighborhood, according to four data scientists from the research group Good City Life, who put together a set of mesmerizing maps called Chatty Maps. By analyzing tags on thousands of public photos, the researchers mapped out the sound profile of streets in 12 cities, including London, New York, Madrid, Boston, and Washington, D.C. On some streets, marked in green, sounds associated with nature dominate. Streets that are predominantly filled with traffic noise or human chatter are marked in red and blue, respectively.
To reach that level of detail, the researchers sifted through thousands of public Flickr photos, identifying each image’s geolocation and taking note of any sound-related words that the photos were tagged with. (The sound-related words are taken from Freesound, the largest crowdsourced online repository of audio samples.) Using an algorithm, the words were categorized into six categories: transport, nature, human, music, mechanical, and indoor sounds.
The team also mapped the correlation between emotion-related and sound-related tags, finding, for example, that human sounds often evoke joy or surprise, while traffic and mechanical sounds are associated with anger and fear.
Take the Foggy Bottom neighborhood of Washington, D.C., where CityLab and the popular John F. Kennedy Center for Performing Arts are located. A click on a street near the office, which has been marked orange, produces charts on the right that reveal music-related sounds to be most dominant, followed by nature and transport sounds.
The creators of Chatty Maps—including the map researcher Daniele Quercia, the social science researcher Luca Maria Aiello, the data scientist Rossano Schifanella, and the acoustic researcher Francesco Aletta—write in a press release that city planners too often focus on the negative effects of urban sounds. That’s true; a lot of research suggests urban noise is a health hazard, with studies warning that it can raise your risk of obesity and take a toll on your mental health. Maps that cover soundscapes have focused on charting noise complaints or pinpointing loud neighborhoods to avoid.
But sound can also have a positive effect on city dwellers, the researchers write, and can be used to create healthier and better-balanced environments. It’s an idea that goes back to the 1960s and 1970s, pioneered by the composer and environmentalist R. Murray Schafer. Still, urban planners have yet to fully embrace sound as a tool. (MIT’s Community Innovators Lab is currently documenting sound profiles across the world, which will yield a wealth of data to work with.) Chatty Maps is a first step toward mapping what sound can reveal about a city.