A noisy neighborhood is no mere nuisance; it can be a major health hazard. Cars, planes, and commercial bustle can disturb sleep, create stress and hearing problems, contribute to cardiovascular disease, and impact cognitive development in children.
So why, when working to improve neighborhoods or choosing where to live, do we give relatively little consideration to sound?
Brendan Farrell, a former Caltech data science researcher, had that realization while apartment hunting in the Los Angeles area last year. As he searched for a pad quieter than his last, he writes, “I discovered that every other type of information imaginable [was] immediately available except information on noise.”
So he took his PhD in applied mathematics and applied it. With the help of a fellow mathematician and two geographic information system (GIS) experts, Farrell built HowLoud, an interactive sound map of Los Angeles and Orange counties.
Punch in an address within the area, and the map offers a “Soundscore”: a local noise level (where higher numbers are quieter, counter-intuitively) based on the “type, time and intensity of noise from vehicle and air traffic, bars, restaurants and many other sources.” It also offers other, more qualitative sound measures, as well as a handy list of local noise-makers.
How does it know? Using a 3-D rendering of the region—accounting for buildings and streets—Farrell and his team determined the “sound profile” of city streets. This is based on a number of different sources, such as vehicle flow at a certain speed and volume, air traffic, nearby bars, restaurants gas stations, sports stadiums, and more. According to the mapmakers:
We then use physics to propagate the noise through the environment. The noise is attenuated as it travels, is reflected off obstacles and has its frequency profile changed. Our model incorporates all these effects and gives the noise level in decibels. The human ear, however, cares about more than just the average decibel level. Time matters: noise in the night is worse than noise during the day. And intensity matters: a low-flying jet is worse than a light steady hum. We incorporate time and intensity factors into an aggregate score that allows users to compare locations.
I checked the map out for a number of areas I’ve lived and worked in around L.A., and the scores seemed pretty accurate, although the map didn’t recognize any of the downtown or South L.A. addresses I entered. And I worry about the “good/bad” judgment that the Soundscore implicitly makes about neighborhoods, as low-income households are disproportionately impacted by noise pollution. HowLoud could give people the idea that they should explicitly avoid low-scoring, “red” neighborhoods. To the contrary, city planners could use the map to home in on areas hurting for environmental justice.
Farrell and his team are still working out the kinks—and they’re also planning a grand expansion. HowLoud recently launched a Kickstarter to raise funds for a sound map of all of North America, so that anyone on the continent can gauge the noise quality of their neighborhoods. Below, more Soundscores from around the L.A./O.C. area: