New Audio Technology Registers Gunshots – And Conversations.

UPDATE 2017:  The gunshot detection devices are now operational in all five boroughs of NYC and are providing invaluable aid in removing illegal guns off of the streets of the city.

From the NY Daily News, March 28, 2017:

Two years ago, the first ShotSpotter gunfire sensors were installed in Brooklyn and the Bronx amid great concern that far too often — about 80% of the time — New Yorkers who heard shots didn’t bother calling 911.

Since then, the rate has improved — with 34% of shootings detected by ShotSpotter also resulting in a 911 call, according to 2016 statistics.

The rise comes as both arrests by police and complaints against officers are down substantially while the department adheres to a new policing philosophy that stresses a closer relationship between cops and the neighborhoods they serve.

Deputy Commissioner Jessica Tisch, the NYPD’s technology guru, said the sea change is affecting the way New Yorkers think about the NYPD.

“We know that based on neighborhood policing that the NYPD is making significant efforts to partner with the communities and we also know that cops are responding more to shots fired jobs because they know about more shots being fired,” Tisch said. “The numbers show more people are engaging with police.”

Sgt. Joseph Freer, who works with Tisch on the ShotSpotter initiative, said that even though the alerts are sent to cops’ smartphones and beat the average 911 caller by almost two minutes, the added value of an eyewitness or earwitness is immeasurable.

“We can’t have cameras everywhere,” Freer said. “We need human eyeballs, so getting that citizen call is just as valuable. We’ll get there quicker with ShotSpotter but I’d still love to tie it to witness descriptions.

“So, we want the people engaged and this increase is very heartening to see.”

Cops said knowing about more shootings gives them the ability to find more guns and more bullets, make more arrests and tie more incidents together.

In 2016, for instance, police responding to 2,399 ShotSpotter alerts recovered guns in 57 incidents — weapons that were either left at or near the scene or recovered during the execution of search warrants.

Most of those incidents — 37 in all — were accompanied by 911 calls. However, 18 were not — meaning that without ShotSpotter those guns would still be on the street, Freer noted.

Many other times, Freer said, ballistic evidence was recovered and linked to other shooting scenes.

The numbers for 2016 haven’t yet been tabulated, but in 2015, “one in five shell casings from a ShotSpotter alert matched a casing from another shooting in New York City,” Freer said.

The NYPD in 2009 tried, then quickly abandoned a similar program with a different vendor because the false positive rate was above 90%, Tisch said.

The program’s first phase focused on the South Bronx and northern Brooklyn.

Early on, it seemed New Yorkers cared little for getting involved, with the reporting rate hovering around 20%.

In one such shooting, in March 2015, someone fired 24 times from an automatic pistol and not one person called 911.

The program has expanded twice since then and will soon be covering 60 square miles, with sensors in each borough, at a cost of about $2.5 million a year.

ShotSpotter sensors, installed in more than 90 cities around the country, are essentially laptop computers with microphones on them. In New York City, they sit atop buildings in high-crime areas.

When a shot is fired the sensors set in motion a process that takes no more than 45 seconds.

A GPS chip pinpoints an exact location and time, then sends the sound recording to ShotSpotter’s California headquarters, where acoustic experts determine if a gun has been fired — or if the sound was made by something else, such as fireworks.

If it’s gunfire, a push of a button sends the information back to the NYPD. Alerts are then sent to officers’ smartphones.

Meanwhile, cops assigned to the Domain Awareness System, the department’s network of data from various sources, are able, with the click of a button, to locate the police cameras near the shooting and view in real time what is happening.

Tisch said that means the immediate aftermath of many shootings — including who fired the gun — is often caught on camera.

“It happens,” Tisch said. “And it happens a lot. And so, more and more, as we build out the camera network in the high crime, high shooting locations we are capturing more of the events that cause ShotSpotter activations.”

End 2017 update.



UPDATE 2016:  We’ve  been keeping an eye on the Shot Spotter audio gun shot detection system that is now being installed in many cities nationwide, specifically to determine if its ability to record conversations has been used in the courtroom.  Below are excerpts from the latest DNAinfo article covering these very questions.

To find out how exactly the technology works, who has access to the data and where ShotSpotter hopes to deploy in the future, DNAinfo spoke with Ralph A. Clark about the company, founded in the mid-1990s with its first gunshot detection system installed in Redwood City, Calif. in 1997.

There are at least two instances — one in Oakland, Calif. and another in New Bedford, Mass. — of ShotSpotter recordings used as evidence in trials. How often does that happen?

Clark: Those are very rare. In those two particular cases, there was someone literally shouting over or just before or just after they got shot. The system clips [the audio recordings] off in the front, so we’ll cue it up and I think it’s one or two seconds before the gunshot event — boom, boom, boom, boom — the gunshot, and then it will play another two or three seconds after. You need that in order for our reviewers to do their work.

In the case of the Oakland situation, because the person, right after he got shot, he said ‘So and so, why’d you do me like that?’ and he yelled it out, so that was heard and picked up by our sensors. There’s nothing we can do about that. There’s no privacy issue at that point because it’s a public setting. If you’re shouting out when you get shot, that’s not presumed to be a private conversation. But I can tell you, that’s extremely rare. We’re essentially publishing 60,000 gunshots a year … and I think there’s been about four times where there’s been someone yelling over or on top of a gunshot clip.

One Brooklyn reader of DNAinfo who lives in an area included in the ShotSpotter pilot program told us he is worried that the technology is a “dragnet” that will increase monitoring of high-crime areas, without necessarily reducing gun violence. What can you say to that person who is worried about mass surveillance of his neighborhood?

Clark: We are a surveillance technology. There’s no getting around that. But it’s a surveillance technology that’s completely passive and we’re only detecting when a felony is in commission. So the NYPD — and us, for that matter — is only getting alerts when a gun is fired or when a possible gun is fired. And when we figure out that it’s not a gun that’s being fired, from a human point of view, we dismiss that and that doesn’t even get sent to the NYPD. And that just allows a level of precision for policing that’s a game changer.

I think the way Mayor de Blasio puts this technology — I think it’s perfect. I think he stepped into the breach, which I’m personally happy about being an African-American male, and said, hey, we are going to eliminate broad stop-and-frisk, but what we’re going to do in replacement of that, we’re going to be much more precise in our response and only respond when we know something is going awry. And that’s where ShotSpotter plays a very significant role. We are interested in being deployed where, unfortunately, urban gun crime exists. There’s no value in us being deployed in a place where people don’t shoot guns and so, that’s where we go.


End of August 1, 2016 update.

shotspotter04.12.2015    Last month, cops in New York City started testing a system that alerts them almost instantly to the location of where a gun was fired to within an accuracy of 25 meters (82 feet).   The ‘ShotSpotter’ technology utilizes strategically placed audio sensors that relay gunshot location information to nearby cops, enabling a rapid response.  ShotSpotter is used in major cities including Washington, Boston, Oakland, San Francisco and Minneapolis, as well as smaller cities like East Chicago, Ind.

The system is also smart enough to predict where subsequent shots may take place, providing officers with additional caution and backup to a “shots fired” situation.

The system was activated in the Bronx on March 18, 2015 and Shotspotter picked up gunshots in just an hour of going live.

Brooklyn Shotspotter went live several days after the Bronx, with the remaining boroughs following later if  the system proves effective.

The results thus far in these two NYC boroughs are disturbing; of the 55 gunshot incidents detected from March 16, 2015 – April 2, 2015, only 12 were called in to 911 – a poor 22% of the time someone called the emergency number to report the gunfire. Comments on the woeful reporting rate,  from the NY Daily News:

Police Commissioner Bill Bratton said he knew from other cities that up to 80% of all gunplay never gets reported, but he thought New York City’s density would mean more people would report gunshots.

“I’ll be quite frank — I’m surprised that we’ve had so few calls to 911 for those shots that have been identified,” Bratton said.

Going forward, cops will make more arrests based on evidence gathered through the technology, he predicted. Police expect to expand ShotSpotter citywide after it analyzes the results of its $1.5 million pilot program.


What the Shotspotter technology does (according to the eponymously named company’s website):

ShotSpotter (SST) instantly notifies officers of gunshot crimes in progress with real-time data delivered to dispatch centers, patrol cars and even smart phones. This affordable, subscription-based service enhances officer safety and effectiveness through:

  • Real-time access to maps of shooting locations and gunshot audio,
  • Actionable intelligence detailing the number of shooters and the number of shots fired,
  • Pinpointing precise locations for first responders aiding victims, searching for evidence and interviewing witnesses.

How the Shotspotter technology works: 

Best explained: Unlike counter-sniper sensors which can only measure a limited range of sounds—the supersonic signature of a sniper’s round with a known ballistic coefficient—SST’s wide area protection system measures the full range of impulsive sounds (sounds which are explosive in nature) found in urban weaponry, from sub and supersonic impulses to explosions.

So basically, the SST technology – given that it is subsonic – can admittedly (by the company) pick up on anything – including conversations – that it is calibrated to monitor.

I was good with the range of Shotspotter functions until the last item.  That of audio recording of the general public’s conversations.  How long before “exceptions” allowing speech monitoring are employed in sensitive places like surrounding courthouse areas, prison courtyards, college campuses??, etc.  The incident scenes themselves.  The argument that could be made in favor of open-air audio recordings would probably be along the lines of expectation of privacy – that presumably, there is none in public areas.

The application of technology and relevant law will be interesting to follow in the coming years.

Pass notes.

BNI Operatives: Situationally aware.

As always, stay safe.