The National Security Agency isn’t the only arm of government that uses high-tech surveillance to listen for trouble. More than 70 cities, including several in South Florida, have purchased technology called ShotSpotter to instantly alert police to the sound of gunfire.
ShotSpotter uses microphones and motion sensors placed on light poles and buildings to pick up on gunshots and other loud sounds and report the exact location to police. The California-based company that markets the service says it is specially engineered to hear gunfire, and won’t pick up conversations unless they’re at a place where a shooting is in progress.
Police say the technology can be especially valuable in high-crime areas where residents don’t call police to report gunfire.
The technology triangulates the shot’s location and can also track a shooter if they flee on foot or in a car. The location is sent to the company’s response center in California and, after a staff member confirms that the noise really is a gunshot, an alert is sent to the relevant police department.
“Our contractual agreement with our clients is that we’ll pick up 80 percent of gunshots inside an outdoor coverage area,” said Lydia Barrett, a spokeswoman for ShotSpotter. “But in nearly all of our cities the number is significantly higher than that.”
The company did not have numbers for false alarms, which were one of the reasons the Broward Sheriff’s Office abandoned the technology two years ago. False alarms are the reason the company now has one of its employees verify shots before notifying police.
Barrett added that the company has not received any complaints about privacy. News reports mention a 2011 shooting incident in New Bedford, Mass., as the most notable incident where someone’s voice was picked up by ShotSpotter sensors. The microphones picked up the sound of people yelling in addition to gunshots. Out of the hundreds of thousands of incidents the company deals with, Barrett said that kind of situation is rare.
“[The individuals] happened to be standing under a ShotSpotter that was on top of a building, while committing a crime,” Barrett said. “Our sensors are passive, they’re high and out of sight. They’re only activated when there’s a loud boom or bang.”
ShotSpotter, which started in 1995, found its way to South Florida in 2010, when the Broward Sheriff’s Office and Riviera Beach police both decided to give it a try. Since then, it was tried out briefly in Miami-Dade County and is now also being used in Miami Gardens and by the Palm Beach Sheriff’s Office.
Miami Gardens police said the technology has been helpful in investigations and has led to some arrests, although they did not specify a number. They have been using the technology since late last year, and began full-time use back in January. They hope the technology can reduce gun-related crime in the city by 5 percent in the next year, after a few months of multiple notable incidents of gun violence.
Deputy Police Chief Paul Miller is confident in the technology, but he recognizes its limitations.
“There are some times that are anomalies, and we’re working with the company to fix the specifics,” Miller said. “We want to make sure those are one-time occurrences.”
A 2008 study in two Virginia cities using SECURES, a tracking system ShotSpotter acquired, raised some concerns over false alarms and other glitches. Peter Scharf, a criminologist at Tulane University who worked on the study, says that while the company’s detection technology and response process has improved since 2008, he thinks cities should carefully consider the cost and how else they might spend that money.
“If the average price is like, $400,000, would you rather have six cops or a ShotSpotter system?” asked Scharf.
A federal grant initially paid for ShotSpotter’s use in Miami Gardens, but this year the city will have to use about $215,000 from its general fund to keep the program going.
Barrett said ShotSpotter used to require cities to purchase the equipment and have police dispatchers monitor the alerts themselves. Since changing their monitoring system, ShotSpotter has also changed its sales policy, allowing cities to subscribe on an annual basis for the technology (which costs about $40,000 to 60,000 per square mile of coverage) and only respond to the alerts once they’ve been verified.
Miller said the city’s staff has deemed the technology “cost-effective” and he believes it aids the police in finding crime scenes when residents hear the gunshots, but don’t call the police.
“When we realized incidents were going unreported because people were apathetic, or had developed malaise, we knew we had to do something to combat that,” said Miller.
The Palm Beach Sheriff’s Office recently announced their acquisition of ShotSpotter, paid for by a federal grant and private donations. Col. James Stormes said he’s confident that the technology’s past glitches are no longer an issue.
“I think when they first came out it was a far greater concern, their screening process has improved since then,” said Stormes.
ShotSpotter’s alerts include an audio file of the shots so officers can judge for themselves.
“And when you listen to the gunfire on the laptop in the car, you can usually tell the difference between an AK-47 and a handgun,” said Stormes.
PBSO primarily chose the program to combat gun violence in the city of Belle Glade, and to deal with a community that, like Miami Gardens, hesitates to call police when they hear gunshots. While he thinks technology will help, he added that there’s no substitute for community support in reporting crime.
“We have to engage the community more to be a partner with us. It cannot just be a police effort,” said Miller.