Sound defines a city, whether it's the din of New York City traffic or calls to prayer issuing from Istanbul's mosques.
Now, you can see what cities sound like with Chatty Maps, a new set of online maps from research group Good City Life.
The site currently features maps of Boston, New York, Barcelona, Madrid and London. Users can click on streets in each city to see what kinds of sounds dominate in that area.
Using what researchers call an "urban sound dictionary," the maps trawl geo-located Flickr photos for tags associated with particular noises. Those sound-related tags are broken into five categories -- transport, nature, human, music and mechanical -- and create visual sound profiles. The maps also link those sounds to particular emotions, giving users a sense of what it might feel like to walk down a particular street.
Though users can only see complete sound profiles for specific streets, the color-coded maps (red for traffic sounds, green for nature, orange for music, blue for people, gray for mechanical) helps give a general idea of what you might hear if you were to walk from street to street in a particular neighborhood.
For instance, New York's Upper West Side, a wealthy residential area near Central Park, appears to be full of nature sounds: (Click here to play with interactive versions of the maps.)
Researchers also used geo-located photo tags to attach sounds to specific emotions. They found, for instance, that streets defined by musical sounds were linked to feelings of joy or sadness, whereas traffic sounds were tied to fear and anger.
The latter isn't surprising. Research on urban sound has found that noise pollution is correlated with everything from sleep impairment to cardiovascular disease.
This section of New York's Park Avenue, a busy thoroughfare, is dominated by transport sounds associated with surprise, sadness and fear:
But other urban sounds, from church bells to street vendors, can also calm, exhilarate or inspire.
The sounds of St. Mark's Place, a street near The Huffington Post's New York City offices, come mostly from humans. The street also contains music, nature and transport sounds, giving it a joyful feel, according to Chatty Maps.