Shots Fired!

A growing surveillance network aims to fight crime by tracking gunshots.

The alert blares from the computer like a ray gun from an old cartoon: WAH-wahwahwahwah. Jonathan, a ShotSpotter analyst, focuses on one of the six monitors in front of him and zooms in on a street-level map of Milwaukee. Next to the map are what look like Christmas trees on their sides–a cluster of green sound waves.

Jonathan, who has spent nearly five years staring down these monitors, says he can tell just by looking that the pattern means gunshots. The audio seems to confirm it with a series of loud pops. The map appears to show that the sound originated from the top of a building, but Jonathan is hesitant to relay that to police on the ground. “I’m a little apprehensive to tell people to go to a roof,” he says. Instead, he simply notes gunshots were confirmed and pushes an alert to the Milwaukee police department. The entire sequence–from the supposed trigger pull in Milwaukee to the analysis at Jonathan’s desk 2,200 miles away in Newark, Calif., to the squad cars of cops back in Wisconsin–happened in under a minute.

That rapid chain of events is the selling point of ShotSpotter, a small public company whose proprietary gunshot-detection technology is being used by a growing number of police departments across the nation. ShotSpotter works by installing specially calibrated outdoor microphones that pick up what CEO Ralph Clark likes to call a “boom or bang.” Those microphones are now in more than 90 U.S. cities, including New York and Chicago, and as far afield as South Africa.

The acoustics analysts are trained to differentiate gunfire from similar sounds like construction noise or firecrackers. When gunshots are confirmed, they send an alert that could reach the cell phone of a cop near the scene in less than a minute. “It’s a weird feeling,” Jonathan says of identifying gunfire. “It’s like you want to see one, but you don’t.”

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