ShotSpotter is a system developed by Newark, CA based company SST that uses a combination of acoustic sensors, algorithm audio analysis, and GPS to help local government agencies and police forces locate gunfire in their city as it happens.

SST keeps many of the details of its system under wraps, but in general the ShotSpotter system requires 10 to 12 audio sensors to be installed on top of roofs or streetlights for every square mile of street coverage. When a loud noise is registered by 3 or more of the sensors the companies cloud service and alert notification systems kicks into action:

  • GPS clock signals from the sensors are synchronized and used to provide location data down to a specific street name.
  • The captured audio is compared to a database of known weapons signatures.
  • Finally, an audio analyst at the SST headquarters reviews the recordings as a last step to minimize false alerts before forwarding the details onto the authorities.

Typically within 30 seconds of a shot being fired dispatchers and police on the ground are provided with details on the number of shooters and shots fired, possible type of weapon used, and information on if the guns were discharged from a moving vehicle.

Some cities are integrating the service with their existing surveillance camera systems so when a ShotSpotter alert is triggered the nearest cameras are automatically panned to the spot of the sound. This live footage can then be streamed to responding police vehicles as another way from them to assess the situation before they arrive on the scene.

Acoustic Gunfire Detection: ShotSpotter
Acoustic Gunfire Detection: ShotSpotter
Acoustic Gunfire Detection: ShotSpotter

Last month the company began to publish an index of gun activity in the United States using the data its systems collect nationally from the 70 cities around the United States that it is currently operating in.

Unfortunately the existing data sources on gunfire activity rely on limited 9-1-1 calls; hospital reporting of gunshot wounds; and the minority of incidents which result in homicides or suicides. As a result, gun violence is significantly under reported—and misreported—at the very moment this critical epidemic needs precise and reliable data from a research perspective,” said Ralph A. Clark, president and chief executive officer of SST, Inc. “Our National Gunfire Index reports all gunfire incidents, even non-fatal and non-injury firearm violence, so you get a truer and more inclusive geographic mapping and accurate intelligence of the factual extent of gun violence.

More information can be found at or by watching the NECN news story covering the city of Boston's system and how it is being used in the video embedded below.

Additional: Wired, Singularity Hub, PCWorld

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