Acoustic Gunshot Detection Tech - the good, the bad, & the ugly

by Mateja Mihinjac

I’ve recently come across a report titled “ShotSpotter and the Misfires of Gunshot Detection Technology” by the STOP Surveillance Technology Project.

The report is extremely critical of this Acoustic Gunshot Detection Technology (AGDT) suggesting it offers little operational value for the police and it can prove detrimental with serious ethical caveats.

How bad is this technology really? 

SHOTSPOTTER®

ShotSpotter Inc. has been on the market for 20 years and it is the leading AGDT on the market used by over 200 police jurisdictions worldwide, with at least 130 of those from the US. 

ShotSpotter prides itself with the slogan: “Right place, right time. Precision policing solutions that help save lives, solve cases and deter crime – making communities safer.”

AGDT technology starts with microphones mounted above
the city on buildings and other tall structures

ShotSpotter combines narrow AI with human experts to identify and locate gunshot events and their location in the neighbourhoods where it’s been installed. Its detection system comprises microphones placed on streetlights, buildings and utility poles, and audio software that compares the sounds with prior gunshot events in its database. The system triangulates the location of the sound that is further reviewed by a human sound analyst who alerts the police should they determine the sound actually derives from a gunshot. 

THE GOOD

Company reports, and some technology reviews, offer that it detects shootings that would go unreported, locates gunshots for quick police response, and improves the arrest rates of suspects. This all leads to preventing gun violence and enhanced neighbourhood safety.

THE BAD

The evidence suggests that many of the above claims can be disputed. For example, while quasi-experimental studies indicated over 80% accuracy in detection and triangulation, other studies show the AGDT works poorly in detecting gunshots and, instead, it suffers from what researchers call “false positives” (it gets it wrong). 

Chicago’s Office of Inspector General review found that only 9.1% of probable gunshot alerts out of 50,000 records over a 17-month period resulted in evidence of a gun-related offence.

While we sleep at night, it listens for gunshots from roof-mounted
listening devices - what could go wrong?

These studies conclude that AGDT may actually be ineffective and inaccurate and can thus waste police resources. None of that mentions the cost, (Chicago paid $33 million for 2 years of service).

As well, there are poor outcomes on firearm offence reduction and shooting victims’ medical outcomes two years following the installation. Thus, it did not lead to gun violence deterrence as anticipated.

Most alarming was whether ShotSpotter evidence should be used in court. The company has previously admitted to altering the records and reclassifying the sounds that were initially not detected and determined as gunshots but were later reclassified as such based on police reports. While this may be occasionally warranted, at other times it may lead to the misuse of data and misrepresentation of the evidence on the side of the law enforcement agencies.  

THE UGLY

AGDT can lead the local community to become disengaged and stop reporting gunshots because they believe the technology will handle that for them. In St Louis, for example, citizen-initiated reports of gunshots before the installation of ShotSpotter were 7 times more useful than AGDT and wasted less police time. Following the installation, citizen reports significantly decreased and decreased further when the system was expanded.  

AGDT is predominantly deployed in poorer and majority Black and Latinx neighbourhoods commonly identified as hotspots for shootings and violence. While there might be more shooting incidents in those neighbourhoods, this automatically means AGDT will detect more shooting incidents in those specific neighbourhoods rather than in other neighbourhoods where it is not deployed. This might perpetuate the problem of over-policing and racial bias in communities of colour. 

Evaluations of AGDT shows problems with "false positives"
- it turns out the city can be a noisy place

There is a similar problem with another narrow AI program called predictive policing where there are reports of racial discrimination and over-policing and the additional concern of “tech washing”.

Despite ShotSpotter’s claim that the sensors cannot record private conversations, there are increasing concerns of the microphones recording regular conversations and acting as a “massive eavesdropping device”.

In one case, such a private conversation in a public space was intercepted and admitted into evidence in a murder trial court case.

Currently, there appear to be no regulations that would prevent ShotSpotter from sharing stored audio recordings.

SafeGrowth works directly with community residents in collaboration with the police to plan their own safety strategies

SMARTER APPROACHES

After two decades, the results of AGDT implementation continue to show few positive effects. In fact, some results are detrimental to effective police work, police-community relationships and community safety.

The evidence suggests that police leaders should err on the side of caution and turn towards approaches for addressing gun-related violence that have a better track record.

One example: combining neighbourhood policing and problem-oriented policing to build police-community relationships, act proactively, and approach the problem at its core. 

Another that we obviously recommend is SafeGrowth. This blueprint for neighbourhood safety planning helps residents help themselves, in partnership with police and using the latest in crime prevention. SafeGrowth provides a platform to help address gun-related violence and other crime and safety problems. 

The documented success story in the New Orlean’s gun-violent neighbourhood of Hollygrove is only one example of how neighbours disrupted gun violence. 

Sometimes the most effective solutions are not technology, they are human-based and neighbourhood friendly. That, we believe, is a future we all want. 

CPTED Conference in Palm Springs - Practical solutions vs public safety theater

The CPTED Conference in Palm Springs is sponsored by 

CPTED/PCAM Canada and CPTED USA, May 7-8, 2024

by Gregory Saville

Some time ago we posted various blogs on the pros and cons of security technology as a solution to crime. Some technologies, we concluded from the evidence, provide an excellent addition to a safe environment as long as they are well-understood by the community and targeted strategically. The K-5 security robot patrolling late-night underground parking might be one example.

But other technologies promise more than they provide. Over a year ago, Mateja wrote a blog on the acoustic gun detection system “Shotspotter” as one example of a technology that had mixed results. Mateja’s blog on the topic wrote that studies “conclude that [acoustic security technology] AGDT may actually be ineffective and inaccurate and can thus waste police resources” 

Now the popular media (and more importantly, city decision-makers) have finally taken up our argument and tell an alarming story. The CNN news stream just reported that critics are sounding the alarm that the ShotSpotter gunfire detection system is ineffective

PUBLIC SAFETY THEATER? 

Despite over a hundred cities employing the technology (one wonders whether those cities used any form of criminological due diligence before their purchase?), it turns out cities like Chicago, Atlanta, and Portland have rejected this security technology. These are cities that direly need some respite from street crime. The article asks whether such technologies are ‘public safety theatre’

The reality is that in places like Houston, that use the technology, out of over 4,000 ShotSpotter alerts, only about 200 turned into arrests. Then again, 200 arrests following a gunfire detection alert isn't unimportant. Is the price tag worth that amount?  That’s a good question and a simple answer might be – yes! Yet, if shots occur in a neighborhood with decent design and friendly community relationships, maybe residents will call the police on their own and report the details. That might just as easily result in an arrest. 

USA/CANADA JOINT CONFERENCE

The webcast on community-building through 2nd Generation CPTED

I recently joined some other CPTED experts in describing an alternative to the tech security solution. We discussed a human-centered approach to safety and security called 2nd Generation CPTED. During the webcast, we showed examples where residents and other community members had a direct, and powerful, role in improving their own safety. We showed examples from schools in Oregon, skate parks in Saskatoon, Texas, and British Columbia, and city planning tactics in Florida and New Orleans. 

This CPTED USA/CPTED-PCAM Canada webcast precedes the 2024 joint conference in Palm Springs, California. To see the latest in technology, how to marry sensible technology with community empowerment, and case studies of advanced examples of crime prevention, register for the May 7-8 conference here.

See you there.

The return of broken windows and other stopgaps

Broken windows theory, often confused with CPTED, is a police strategy to cut crime
- photo by Smallbones, Creative Commons

by Gregory Saville

Last year, in frustration over increasing incidents of violence, the NYPD returned to their broken window theory to cut crime, a much-criticized program from the past.

Can cops really prevent crime? There is a big difference between responding to emergencies and apprehending offenders, versus preventing crime. They are not the same. 

If you ask the Frustrated or the Cynical, they say no! Crime goes up and down regardless of police actions. Even people like urban writer Jane Jacobs said that police, while important, are not the main way to prevent crime – people in the community are. 

If you ask the Supporters or the Optimistic, they say yes! Problem-oriented policing seems to cut crime, at least in some cases. But it is a rare strategy in policing nowadays.

What of other strategies? Consider predictive policing and especially hotspot policing, a tactic that goes back decades. When I was a cop we called this showing-the-flag in troubled areas. Flag showing put cops into high crime areas at just the right time.

Some researchers, like criminologist David Weisburd, are big hotspot policing advocates. He points to research that shows early success. Still, there are plenty of questions. When Denver police tried it, they cut gun crime in 3 of 5 hotspots, but citywide gun crime increased anyway.

POLICE CRIME PREVENTION

What about crime prevention officers? Crime prevention specialists do some good work, but they are a tiny fragment of the total police roster. They split their time between a myriad of disconnected programs and they seldom work within the operational goals of a neighborhood-based safety plan. 

What about technology? The research is not convincing. CCTV in public places, for example, has a spotty record with dubious results. We have blogged on CCTV before. We've also blogged on the problems with Shotspotter Acoustic Gun Detection technology. The NYPD domain awareness system is the latest technology in this regard. Unfortunately, crime in NY is still increasing.

What about tough-on-crime like zero-tolerance enforcement, stop-and-frisk tactics, and broken windows policing? Does it work? The research is inconclusive. In fact, parts of the NYPD stop-and-frisk strategy were ruled unconstitutional by the US Supreme Court. 

TOUGH ON CRIME? 

Tough-on-crime programs rely on what criminologists call deterrence theory – strict prison sentences, mandatory sentencing, and other punishments. Deterrence theory has one of the longest research histories in criminology. It shows that deterrence does not prevent much crime! It might work on minor infractions like speeding. But for hardcore criminals, substance addicts, gang members, and others, it does little. 

Jail is also part of deterrence theory and while it may incapacitate an offender for the duration of the sentence, without intensive programming (like Colorado’s horse whisper program) and post-release supports, results are discouraging. If a convict exits prison and returns to the same blight, poverty, and desperate conditions that led him or her to prison in the first place, not much will change. 

Great programs exist but they are too few and too underfunded. 

Fire prevention...not the same as crime prevention. But close enough!
- photo Hungryogrephotos Creative Commons

FIRE PREVENTION

In the final analysis, stop-and-frisk, hotspot policing, CCTV, tough-on-crime, and many others are little more than stopgaps. They calm the winds, but the hurricane continues. 

Fire prevention takes a whole different approach. Fire officials learned long ago that driving around blindly on random patrol waiting for the fire was futile. They might send fire specialists to places where fires often break out – fire hotspots (pardon the pun), and then dispatch the engines. But those are nothing but stopgap measures.

Instead, they learned about the root causes of fire, the materials, and the types of situations where fire was likely. They developed preventive education about risky situations, like smoking in bed. They created building codes with fire-resistant materials and regulations requiring extinguishers in new construction. That is how they prevent fire. They dug at the roots and used scientific knowledge about the causes.

Paradox: noun - par.a.dox [a statement that is self-contradictory or logically untenable] 

THE CRIME PREVENTION PARADOX 

It may not be exactly the same as crime, but it is close enough! And that leads to the conclusion that all the stopgap measures above have one simple paradox: In order to work, those measures need already-committed crimes. There can be no crime hotspot unless existing crime already makes a place hot. Crime prediction is impossible unless you already have an existing pattern of crime from which to make your predictions.

The paradox gets even worse when you deploy stop-and-frisk, showing the flag, or tough-on-crime, all of which show up in the hotspots where poverty, inequities, blight, and fear already exist. Stopgap programs are unlikely to prevent those things that have existed for decades. You cannot prevent something that already exists. You can mitigate it once you discover it and stop it from recurring. That is all fine and good. But it is not prevention, per se. 

The fire people are right that to prevent something, you must understand and diagnose it. You must have a local, long-term plan with specific goals. 

This deeper and more comprehensive fire prevention method is more difficult with crime because the causes of crime are complex and multi-faceted. Of course, that is no excuse to stay confined within the walls of stopgap measures. There are more collaborative ways to build communities out of crime. 

WHAT NOW?

One answer is to get the police to collaborate with neighborhoods on the kind of community-building we describe in SafeGrowth: Building Neighborhoods of Safety and Livability. This method has been well-established and previous books have outlined early versions, such as Paul Grogan and Tony Proscio’s Comeback Cities: A Blueprint for Urban Neighborhood Revival.

Another answer, also linked to SafeGrowth, is Bill Geller and Lisa Belsky’s Building Our Way Out of Crime. That too describes deeper ways out of stopgaps and towards more comprehensive prevention. 

Bill Geller and Lisa Belsky published their summary of community transformation. An abbreviated summary is at POP Center Library. The full book is available online

All this points toward one particular answer to the question: Can police prevent crime? There are ways for police to prevent crime and all of them start and end with collaborations directly with the community.