Somewhere in San Francisco's Mission District, they say a solar-powered phone is concealed in a box atop a pole. The phone is running Shazam—an app that identifies songs—with a microphone trained on the street below. If you visit walzr.com, you can see what music has drifted into the mic's range, hear fragments of the tracks mixed with ambient street noise, and click links to hear the full songs on Spotify or Apple Music.
The man behind this is Riley Walz, a 22-year-old programmer with a history of prankish projects, such as tricking Twitter into verifying a fake congressional candidate. He calls this one Bop Spotter, after ShotSpotter, a controversial company whose sound sensors can allegedly pinpoint a gunshot's location.
