California Tech Company Behind ShotSpotter.
SESAY: Welcome back, everyone. the tech world is joining the fight against gun violence in America. ShotSpotter listens for gunshots to try and direct police to crime scenes faster than a 911 call. Our Samuel Burke visited a police department in New Jersey to see how they are putting the technology to use.</s>SAMUEL BURKE, CNN CORRESPONDENT (off camera): Gunshots in one of America's most dangerous cities: Camden, New Jersey. Within seconds, and without even a call to 911, the police know exactly where the shooting happened.</s>GABRIEL CAMACHO, CAPTAIN, CAMDEN COUNTY POLICE DEPARTMENT: The way it works is you have microphones throughout the entire city. They pick up on sounds of gunfire, and not a matter of hours or minutes but even seconds it will take that sound and triangulate it and send it to main system ShotSpotter, come back with a location and even give us a difference whether it was an actual gunshot or even a firecracker.</s>BURKE: And it's telling you all of that right here, in your car?</s>CAMACHO: We saw that information real-time and we are directed to, not within miles or blocks, but, you know, a matter of feet.</s>BURKE (off camera): California company, ShotSpotter, is placing its listening devices on rooftops and light posts in high crime neighborhoods. It wouldn't show us the microphones, hoping to keep people from finding them and disabling them. To be effective in the city how many of them do you need dispatched?</s>RALPH CLARK, CEO, SHOTSPOTTER: We deploy (inaudible) rays of 15 to 20 sensors per square mile, depending on the environment that we're in.</s>BURKE: How can your system hear the difference between a gunshot and a car backfiring?</s>CLARK: We have trained human experts there, listening to these particular events and confirming that they are gunshots. Although, our machine algorithms are really, really good, they are not perfect. We know that humans, even though they're not perfect either, they are better than the machine. So we think it's a small price to pay, in terms of time. You're talking about 15, 20 seconds to make sure we're not pushing over false positives because that's a bit of a deal killer.</s>BURKE (off camera): With microphones listening in on a city 24/7, many police departments now realize just how much gunfire has gone unreported.</s>J. SCOTT THOMSON, CHIEF OF POLICE, CAMDEN COUNTY POLICE DEPARTMENT: Before, the community wasn't calling and telling us about the overwhelming majority of gunshots that occurred; but now, even when people were calling in, many times we were responding to the scene quicker than they were even getting the phone call into us.</s>BURKE: Some people worry about this technology. Okay, so it's telling you where crime is happening but has it actually changed the crime levels and brought them down, do you think?</s>THOMSON: When you look where we initially started with ShotSpotter, the first square mile we utilized, it was, statistically, probably the most challenged square mile in the United States of America. We've been able to significantly drive down gun violence within that neighborhood. Now ShotSpotter has been a piece of a puzzle along with Community Policing efforts.</s>BURKE: What about privacy, when you start talking about listening devices in the lights it does make people fearful about Big Brother?</s>CLARK: As opposed to video surveillance, which, you know, looks at everything, even if nothing is going bad and then retaining that data for a long time. If you think about what we do, we're acoustic only. We're acoustic 30 feet up in the air. We do all manner of things to our sensors to essentially baffle ambient noise and pull out, you know, impulsive noise. We only keep the gunshot data, you know, the two seconds before and the four seconds after. Everything else gets thrown out.</s>BURKE (off camera): These systems are not cheap. ShotSpotter charges as much as $100,000 a year, per square mile of coverage. 90 cities across the U.S. are trying out the service now. For Camden, the fees are worth it; using technology to try and transform modern day policing. Samuel Burke, CNN Money, New York</s>SESAY: Fascinating report there. Well, thank you for watching "CNN NEWSROOM" live from Los Angeles. I'm Isha Sesay. "World Sport" is up next. You're watching CNN.