AEG-Electrolux has installed billboards outfitted with sensors to measure noise levels. So far, they've deployed them in London, Berlin, Madrid, Brussels, and Milan. The billboards are part of a "noise awareness" campaign that's actually a marketing effort for a new "silent" washing machine. The data is also viewable online. Link to AEG Noise Awareness Blog, Link to AEG Noise Awareness site, Link to more info and video at Laughing Squid
David Pescovitz is Boing Boing's co-editor/managing partner. He's also a research director at Institute for the Future. On Instagram, he's @pesco.