Park sounds before and during the pandemic

With lockdown orders arounds the world, places that we’re allowed to go sound different. The MIT Senseable City Lab looked at this shift in audio footprint through the lens of public parks:

Using machine learning techniques, we analyze the audio from walks taken in key parks around the world to recognize changes in sounds like human voices, emergency sirens, street music, sounds of nature (i.e., bird song, insects), dogs barking, and ambient city noise. We extracted audio files from YouTube videos of park walks from previous years, and compared them with walks recorded by volunteers along the same path during the COVID-19 pandemic. The analysis suggests an overall increase in birdsong and a decrease in city sounds, such as cars driving by, or construction work. The interactive visualization proposed in Sonic Cities allows users to explore and experience the changing soundscapes of urban parks.

The 3-D view shown above is visually interesting, but the top-down view is the easiest to read, looking like a stacked area chart over a map.

At distinct points on the mapped paths, a gradient line represents the distribution of quieter and louder sounds. Louder sounds appear to take up more space during the pandemic.

It’s hard to say how accurate the sound classification is through this view, but as I poked around, it seemed a bit rough. For example, the chart for Central Park in New York shows bird sounds making about 0% of the footprint, but you can hear birds pretty easily in the audio clips. I’d also be interested in how they normalized between YouTube clips and their own recorded audio to get a fair comparison.

Nevertheless, it’s an interesting experiment both statistically and visually. Worth a look.

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Finding small villages in big cities

Urban Village

Daily life in cities tends to differ from daily life in small towns, especially by who we interact with. The MIT Senseable City Lab and the Santa Fe Institute studied this social aspect — individuals' contacts by city size — through anonymized mobile phone logs. As expected, those in cities with greater populations tended to have more contacts. However, when the researchers looked at who knew who, the results were more constant.

Surprisingly, however, group clustering (the odds that your friends mutually know one another) does not change with city size. It seems that even in large cities we tend to build tightly knit communities, or 'villages,' around ourselves. There is an important difference, though: if in a real village our connections might simply be defined by proximity, in a large city we can elect a community based on any number of factors, from affinity to interest to sexual preference.

Read the full paper for more details.

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