Today's show is interrupted by impeachment coverage but can be heard on the Standing Wave Radio webstream at wavefarm.org/listen. Today: A dive into an archive of collected noises from 10 megacities across the globe. Interviews and ruminations will be mixed in with these sounds, in search of a better understanding of a fundamental question: "what is noise? About this month's broadcast, Paulus van Horne writes, "The history of PA systems is surprisingly well-chronicled on Wikipedia. For more information about the politics and power of sound in general, the following books were influential in the creation of this program: Beyond Unwanted Sound by Maria Thompson and Sonic Warfare by Steve Goodman."