ShotSpotter Gunshot Detection System

The NY Times have published an interesting article on the ShotSpotter Gunshot Detection System …

A technician quickly focused on the computer screen, where the words “multiple gunshots” appeared in large type. She listened to a recording of the shots — the tat-tat-tat-tat-tat of five rounds from a small-caliber weapon — and zoomed in on a satellite map to see where the gun had been fired: North 23rd Street in Milwaukee, 2,200 miles away.

Cities that installed ShotSpotter in the past bought the equipment and managed the alerts themselves, a model that often involved laying out hundreds of thousands of dollars. But the company now offers a subscription plan for a yearly fee of $40,000 to $60,000 per square mile that includes round-the-clock monitoring of alerts by trained reviewers here in Mountain View.

Ignoring any legal, social and constitutional issues of such a system, I wonder what effect this system would have on gun ownership and perception of gun owners.

If the system worked 95% of the time (and by work I mean it detected the shot and officers actually arrived on the scene within 5 – 10 minutes), or at least was perceived as working by criminals, either they would replace their illegal guns with blunt, edged or bow weapons or they would start using homemade suppressors.

If criminals started using edged weapons, legal gun owners would be less easily vilified. If criminals started using suppressors, even DIY suppressors, it would freeze or reverse all progress made over the past few years at making suppressors an acceptable part of shooting culture in the USA.

My biggest problem with the system is the limited areas it could be used. I doubt that it could detect shootings indoors and so would be limited to gangland shoot outs. My other concern would be the ease that the system could be hacked. It would be trivial to set the sensors off and divert police resources using a pair of cheap blank firing revolvers.

I am interested in what y’all think of this system.

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • DrewN

    I want to see the effectiveness stats on this. Like you said, any organized criminal gang could easily spoof this if they really wanted to. For instance my neighborhood is predominately hispanic and loud strings of powerful firecrackers are the norm here. I worked for years at a dropzone literally across the street from a busy outdoor range and even I’m fooled occasionally by the sound.

    • charles222

      Organized gangs? Hell, one of these show up in my neighborhood and I’m throwing an M80 at it every day just to piss off the cops. :p

    • Chase

      Do Hispanic types tend to use fireworks more often than others? I had no idea. You learn something new every day. 🙂

  • Lex

    I don’t believe that, strictly speaking, there are any constitutional issue here, though I’m willing to be convinced otherwise. The sound has left your property by the time it reaches the listening devices. The same precedent that protects cops looking through people’s trash would protect this system on a legal basis.

    • Komrad

      See Kyllo v. US.
      Police used thermal imaging to detect marijuana heat lamps in Kyllo’s garage. Police argued that the heat waves had left his property and were no longer protected, the SCOTUS disagreed and Kyllo went free because they did not have enough other evidence for the case (or actually the warrant leading to his arrest) to stand.
      The SCOTUS likened it to placing a bug on the outside of a telephone booth. Although the sound waves had left the booth, there was still reasonable expectation of privacy and it constituted an illegal search.

      Now, I’m not sure if this would fall under the same precedent or not because in Kyllo’s case, the issue was that the heat could not be observed by normal means available and in common use for the average citizen. The average citizen could certainly hear gunshots, but I wonder if the triangulation could cause issues.

      My first instinct is that this would be constitutional, but I don’t think that using it as the sole basis for a warrant would be, simply because I doubt the strength of the evidence (fire crackers and blanks sound like the real thing).

  • Lex

    Gangland cops have no reason to care that the system is impractical to deploy in the open prairie. The “tactical team” in the first story is stupid since it could have been nothing. The second example is much better, have a cop swing by the area to see if anything is happening and call for back up if there turns out to be an issue, make a more effective use of limited resources.

  • Broward County Sheriff pulled the plug on theirs. Too many false alarms

  • C3P0

    firearms, not politics . . . WTF?

  • eichenlaub

    Waste of money

  • Assuming that it actually worked it Seems like a slippery slope that would likely be abused. But so are domestic drones. I recall that the military has something like this for spotting snipers but it seemed to be more accurate as it tracked both the audio of the shot and the sonic boom of the bullet.

  • Bob Z Moose

    What if someone set off an M-80 or other fire cracker? What about echos in bigger cities with tall buildings? How recognizable are the sensors and how fragile are they? Could you take a sensor offline by putting something over the top of it or by cutting a cord? Since the system probably uses triangulation, if one sensor goes down, how accurate is the system with one or two sensors? There’s a ton of questions and things that could go wrong with this system. I don’t think you can put it on the same level as cameras in public places or roads or drones, but it seems more like something that that will cost a ton for cash strapped police departments that either isn’t effective or offers little advantage over community involvement campaigns. Seems like this would encourage criminals to conduct more home invasion style attacks to eliminate someone they want to get rid of, rather than shooting them on the street (since it doesn’t seem to work indoors). I guess that DIY suppressors could become a problem, but I don’t think you would see a lot of them. You don’t get into the position of being a thug by having mechanical aptitude or much in the way of intelligence. Overall, good concept, bad in practice.

    • noob

      good question.

      another question would be:

      even suppressed bullets make a hiss when they part the air. Can it determine the flight path of a suppressed subsonic bullet?

      it must definitely be able to track the crack of a supersonic bullet, or it’s nothing more than a glorified baby monitor.

      • Lex

        It’s not detecting the “path” of anything, only the point of origin.

  • Kevin

    Not many studies out there. But here’s one that showed a 33% false alarm rate, but in general it was easy for dispatch to determine that they were false.

  • Ted

    ASSUMING THE SYSTEM WORKS, I would support giving up our right to suppress a weapon so that criminals would be driven away from using firearms in general.

    -While both useful and cool, suppressors do not contribute to our rights to self defense, or our means of defending the country as a militia as the Founders intended.

    -While not difficult to improvise, I would wager that 90% of gun criminals would not end up finding a way to suppress their weapon.

    • Komrad

      *CRASH* *BOOM*
      Oh no, is that a burglar? I’d better grab my trusty AR-15.
      I’ve got a gun, I’ll shoot!


      You now have permanent hearing damage because yo fired an unsuppressed weapon in an enclosed space. If you’d had a suppressor, your hearing would be intact.
      Suppressors are a wonderful tool for those who wish to protect their hearing when they can’t get their hearing protection on fast enough or when hearing must be preserved and unmuffled.

      • JM

        That’s a common defense for husbands to justify suppressor purchase to their wives, but in reality they are not practical.

        Most people would rather their home defense weapon not have an extra 11″ at the muzzle – not to mention the extra 4 oz.

  • Jersy
    (or google “ShotSpotter effectiveness”) – Pretty much makes all the points.

    As for my opinion – yes, the system probably can detect and localize gunshots, that might otherwise go unreported and it can be more accurate, than citizen reports (in terms of location and gunshot pattern – how many shots were fired, what weapons have been used…). However, it can also react on bunch of other noises and it won’t reduce the response time to the point where any random shooter wouldn’t have time to dissappear in the streets again. It also needs extra staff for monitoring the alerts and extra maintenance.

    Therefore, I would say that the benefits of using this out in the open streets are not enough to compensate for the downsides, but ultimately, it’s up to any local government to decide, if they want to invest into something like that and then assess if it’s actually worth the money.

    As far as criminals and their choice of weapons goes, I don’t think such system would affect anyone but the most serious of proffesionals bent on getting that “Silent Assassin” rating for not triggering any alarm. Your everyday thug would still use a gun, because even if he uses it to anything more than just threatening you, he can still be gone long before the police comes.

    As for suppressors – Basically, I think that an honest man shouldn’t have to worry that his shots will be heard loud and wide, and therefore I would ask myself why on earth one might need a suppressor. While there might be some genuinely non-criminal reasons (not wanting to bother your neighbors with noise, while you shoot at cans on your backyard, or wanting to look tacticool in front of other people), I would certainly be more incilned to think of the suppressor as of a thing that is supposed to allow you to shoot at people and get away with it.

    Therefore, I wouldn’t mind if ShotSpotter system ultimately increased the security measures concerning the suppressors.

    That being said, criminals by definiton break the law, so it stands to reason they would break even laws limiting their access to suppressors. And even if they couldn’t get their hands on one, they would simply find another way to perform a silent kill.

    In short:

    Having a supressor doesn’t increase your murderous tendencies.
    Having murderous tendencies increases your need for a suppressor.

    So, obviously, there should be at least some regulation, in my opinion.

    • Komrad

      *CRASH* *BOOM*
      Oh no, is that a burglar? I’d better grab my trusty AR-15.
      I’ve got a gun, I’ll shoot!


      You now have permanent hearing damage because yo fired an unsuppressed weapon in an enclosed space. If you’d had a suppressor, your hearing would be intact.
      Suppressors are a wonderful tool for those who wish to protect their hearing when they can’t get their hearing protection on fast enough or when hearing must be preserved and unmuffled.

      • JM

        That’s a common defense for husbands to justify suppressor purchase to their wives, but in reality they are not practical.

        Most people would rather their home defense weapon not have an extra 11″ at the muzzle – not to mention the extra 4 oz.

      • Nater

        Extra 11″? Maybe if your home defense weapon is a Barrett M82A1.

      • Komrad

        It’s also a decent reason to own a suppressor. The fact that it works to justify one to your wife is just icing on the cake.
        Another good reason to own a suppressor, they allow you to shoot without disturbing your neighbors, be they two or four legged.

        Also, it’s more courteous for hunters to use them, not only to avoid disturbing others who wish to enjoy the quiet of the outdoors, but also to other hunters. A suppressed gunshot wont disturb as many animals so other hunters can enjoy a good hunt too.
        I Europe, suppressors are often encouraged or even mandated for hunting, and with good reason.

      • Mike

        Hunting and target shooting are other great reasons to own suppressors. Texas just Ok’d suppressors to hunt game animals. It’s going to prevent a lot of hearing damage, and the fact that suppressors eliminate a ton of recoil is good for younger hunters who’ll be out along with Dad.

      • W

        I agree. People need to stop fucking playing video games and watching 24. Silencers don’t completely silence a weapon. With a AR15, and especially a SBR, silencers barely work well enough to allow you to fire without earplugs. Their intention is to reduce muzzle flash and reduce the noise signature down to the ambient noise level, such as in a city. I believe the average is in the ballpark of about 20-30 decibels depending on the model. My AAC for my SCAR 17 SBR has about a 25 db reduction and its six inches long.

        Silencers/Sound suppressors…whatever…are highly useful for home defense. For one, they keep you from being blinded by your muzzle flash and they also limit the noise to a level that doesn’t muzzle blast your eardrums. What they don’t to is completely silence a handgun or rifle enough to make you a stealthy killing machine with destructive abandon.

        Suppressors can be usefully applied for hunting and recreational shooting, in order to allow the operator to fire without earplugs or some kind of ear protection. That stuff gets unwieldy in long hikes in the woods (I hate my Peltors for this exact reason, normally I just use foam ones).

        Yeah sound suppressors are typically 5-7 inches (

  • S O

    “…or at least was perceived as working by criminals, either they would replace their illegal guns with blunt, edged or bow weapons or they would start using homemade suppressors.”

    You overestimate them. Most criminals are stupid.

    Many of them still leave fingerprints, still show their face to CCTV, rape without condom, pursue their “business” in their home city and sell their booty in their home city, brag about what they did, …

  • Big Daddy

    I live in New York City, PLEASE install a system like this.

    I’m tired of reading in the News of 8 year olds taking rounds.

    Maybe this will make the Mayor let up on gun ownership a bit. Not only are the laws restrictive just the paper work and getting it OK’d is a beetch!!!

    • Reverend Clint

      this doesnt stop people from getting shot… its not psychic. The 8 year old could still be shot just as easy if the system is not in place… finding out where he was shot might be a little easier.

      • Zermoid

        Only good point I can really see is that those shot might get aid quicker, as they wouldn’t have to rely on a bystander to call 911 to get help on the way.

    • Big Daddy

      Well DUH….no kidding freakin’ genius.

      It’s called preventing and maybe catching them……DUH OH.

      It’s called easing up on gun restrictions in the city because the mayor is an A hole.

      • Mike

        It doesn’t work in any of the other cities it’s been installed in. Apparently Chicago wound up taking the system down because it was actually hurting response and just costing them tons of money.

    • I don’t know which part of NYC have the most crime, but in any dense urban neighborhood I don’t think this would work (without significantly increasing the number of microphones, cost and false positives)

    • How about putting criminals behind bars instead?

  • matt

    Chicago has the system, it was so crappy that they mothballed it

  • matt

    Chicago has the system, there were so many false positives that they mothballed it

  • Charles222

    We had the Boomerang system in my MRAP on my fourth deployment. It could detect shots. It could also detect the jackhammer that was going every day on our usual mission route. Led to some excitement. :p

  • $60,000 per square mile for unproven technology! Holy crap that’s a lot of money! A city could almost hire another cop per square mile the price of this system.

    • Zermoid

      Probably more, depending on how many square miles the city is!

  • armed_partisan

    To preform a hit without suppressors with this system in place: have your friends and fellow thugs set off fire crackers at the point furthest from your intended target. Coordinate each other via cell phones. Shoot intended victim, and walk slowly away. You’ll probably have at least 10 minutes before the first police cruiser in that area returns. To test this, feel free to set off fireworks or drop heavy objects out of windows several times during the previous month to discover average police response times.

    Or just use a knife. It’s New York City. The chances of running into a law abiding citizen who has a legally concealed firearm are less than your chances of winning the lottery.

  • AndrewL

    I wouldn’t be comfortable with a permanently-installed system. I already dislike cell-phone tracking, especially as I’m required by work to carry one. (Disaster recovery; I’m on-call 24/7.)

    There’s also, in my opinion, the possibility of a slippery slope weakening the Fourth Amendment. If they can react to gunfire now, it would be all to easy to say “Well, we track gunfire; why not this other thing? It’s the same basic idea.” If it’s sensitive enough (theoretically) to determine the type and location of a firearm discharge, it seems to me a later generation would be sensitive enough to passively track things like cell phone rings or voices.

    I would support something like Boomerang’s tracking system ( on cruisers and other response vehicles, however. Once a dispatch has already been made, it would useful for tracking, and a safety system to pre-emptively alert response personnel of gunfire in their area.

  • Nathan

    No way. Waste of taxpayer dollars. There’s no practical way to distinguish a gun shot from other forms of rapidly expanding gas (dropping a 2×4 onto a flat surface, for instance). My guess is that even supressed firearms may be able to be detected, as even a hearing-safe level of noise can still be pretty loud (anything below 140 dcb). But again, that raises the issue of false positives and the huge potential for wasted police resources. And at $50,000 per square mile? That’s a very expensive waste of time.

    In the meantime, one thing it would do is give politicians one more reason to keep their stupid, arcane laws governing suppressors in the USA.

  • cc19

    “…yearly fee of $40,000 to $60,000 per square mile that includes round-the-clock monitoring of alerts by trained reviewers.”

    Waste of tax dollars. Use that money to keep repeat offenders locked away for good.

    • Zermoid

      How many extra cops could that money be used to pay instead? I’d rather have more cops on the street than this system……

      • kadi

        in my city the avg. cop salary is $ 170,000 per year.

    • Reverend Clint

      hell even if they hired a couple mall cops it would be more effective

  • Reverend Clint

    How well will this system work in rush hour traffic with all the hussle and bussle and between skyscrapers? Seems like a waste of time and money.

    • Reverend Clint

      what happens when gangs just have 5 guys go to opposite ends of a city and start shooting at random stuff while the other gang members go murder somebody. Or do like others have pointed out just use a knife or baseball bat like they do in england.

  • Nater

    I highly doubt that this thing works in real life. Just imagine the amount of false positives.

  • JC

    I can’t imagine that this system can tell the difference between a gunshot and, say, a car backfiring, or a pellet gun. I would think that the police would waste a lot of time responding to non emergencies rather than actually policing the streets. Not to mention the costs – $40,000-$60,000 per sq. mile? Why not hire some new policemen for that much money?

  • Rat

    Personal experience with similar type system in Scotlandville, LA. It never worked b/c neighborhood was SO bad Baton Rouge PD would literally wait 15 to 20 minutes before responding on purpose b/c they were often responding alone. No solved crime, just more wasted tax money.

  • tincankilla

    I’m in DC where this system is in place and I don’t object to it. We have lots of shootings here in high density crime areas – if it helps the police get there faster and get the idiot responsible, go for it. In the meantime, I’m saving up my pennies to buy another gun for myself….

    • Totenglocke

      That might work in DC where the Constitution doesn’t apply and therefore legal gun use is outlawed. However, in the US, it doesn’t fly because citizens have the right to own and use guns.

  • abprosper

    No. As Ian welsh put it (paraphrasing here)

    “this and all types of constant surveillance are, simply, the hallmarks of evil regimes.”

  • Moriarty

    Anyone with a rudimentary knowledge of signal detection theory knows what a crock this idea is.

    Responding to false positives leads to wasted resources and increased expense that you have to justify to the taxpayers. (The system costs a lot and doesn’t save money.)

    False negatives force agencies to justify the cost of a system that “doesn’t work.”

    This isn’t even taking into account the fact that spoofing can be coordinated over a broad area using cell phones, texting or other means. (Broadcast a simple code that means: “Everybody dump a magazine in the air now!”) Spoofing could also be automated using cheap, disposable radio transmitters and pyrotechnics.

    Add to this the fact that you’re dealing with criminal suspects with rights. You can’t simply launch a Hellfire at the source because your software decided the sound profile met a certain criteria; you have to pay actual human beings to show up and investigate or the system is worth nothing.

  • DRod

    For the cost and the ease of work around, I’d say no.
    Pretty simple to have a cronie pop a few across town in an alley and drive off.

  • Mike

    I’ve yet to see any evidence that the system works as far as getting police to a scene in time to do anything useful. They were putting these systems in cities back in California before I left, and trumpeting how great they are.

    One of those cities is Oakland. Find me an article that shows Shot Spotter working. You can’t, because it isn’t.

    If the system was working, you’d see reduction in violent crime. You don’t. If the system was working, you’d see a huge PR campaign highlighting the cases where it worked. You don’t.

    It’s just another multimillion dollar waste of taxpayer money.

    • Not That Mike The Other Mike

      I wonder if this thing can be fooled with large firecrackers the local kids love to throw around right after New Year.

  • Rational

    How is there a constitutional issue here? Nothing with Shotspotter precludes you from owning a fire arm. It’s almost like you folks think there is a constitutional right to firing your Glock Fotay out your car window at someone standing on a corner. East Palo Alto has had Shotspotter for some time and it has yielded some positive results. And what is it with you geniuses thinking that your average idiot low life is going to think “I need to figure out a way to spoof Shotspotter!” They’re low lives, they don’t think about that, what do you think makes them low lives? What, you think they got SAT scores of 1,500 or something that’s why they’re slinging rocks on the corner?

    • Komrad

      The issue is not right to bear arms but privacy. There is the potential for something like this to interfere with privacy rights, even if it is unlikely.

  • Zermoid

    Perhaps in a “City” where discharging a weapon is both dangerous and illegal it would be useful, but out where I live it would be going off almost all day! It’s rare for you not to hear someone shooting somewhere around here during daytime!

    I have a nice little hillside in my backyard that we shoot 22’s into fairly regularly and bigger guns on occasion as well. Cops would get tired of coming out to see that we are target shooting after a week or so….

  • Ft. Defiance

    This is in use in parts of Glendale AZ. It’s only value seems to be in tamping down celebratory gun fire. In Arizona we tend to celebrate holidays,birthdays,weddings,Quinceañera’s and BarMizvahs by shooting into the air.
    I have never heard of the system alerting the police to a homicide or agg assault. If a crime occurs indoors the noise is muffled and the system useless. If shot’s are exchanged out doors a dozen hands reach for cell phones.

  • W

    I guess illegal wiretapping, legal outsourced wiretapping (from Canada and the UK), UAVs, thermal imaging, militarized police forces, and the jackbooted alphabet soup federal agencies arent enough. Oh, more porno scanners and CCTV cameras too! Might as well go all out…

  • Jacob

    I’m reminded of the portrayal of Hong Kong in “Deus Ex” (the first one, not the one that was released last year). The police there had installed a similar system to this one, and, being a sci-fi dystopian depiction of Hong Kong, gang warfare had become more or less a kungfu action movie where everyone was fighting to get an experimental sword made of self-sharpening cold liquid metal.

  • Ryan

    The system works, when you have to money to support it. Harrisburg, Pa is now cash strapped and their system is out-dated and to costly to bring back up to speed.

  • John Doe

    If it works, I’m all for it. I’m sick of criminals doing stupid things that give politicians more ammo against gun owners.

    But for 40-60k per square mile, you might as well put another cop around there.

  • davethegreat

    Who cares if it’s easy to spoof/hack/fool the system? Bad guys can do that NOW. Have a crony across town fire a couple rounds as a distraction, a bunch of people call it in and the end result is the same. Shots reported. Does not matter if spoofing is done through an automated system or through the public reporting it. That argument is entirely pointless no matter which side of this issue you are on.