In the last 24 months there have been 200,000 noise complaints logged by the 311 New York city service hotline. This averages 274 calls a day, 1 for every 84 New York City residents in a given year, and accounts for a third of 311 calls to the NYPD and the Dept. of Environmental Protection in the city. 'Keeping the Noise Down' is a project concerned with the development of autonomous, energy harvesting, non-toxic and recyclable environmental wireless sensors, which can be used for recording real-time street-level noise. The sensors are solar powered, using novel organic photovoltaic (OPV) technology from Molecular Solar, a Midlands-based UK start-up; the wireless sensors, which also use greener technology in the form of silicon-based battery alternatives, have been developed by the Univ. of Warwick. The novel noise sensors will be prototyped in a New York-based deployment, made possible through collaboration with the Center for Urban Science and Progress (CUSP).