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Leveraging Technology to produce Societal Benefits
As technology continues to advance, balancing its benefits against some of its inherent risks to privacy continues to be an issue which confronts us all. What’s true for technology in general is also the case in the realm of public safety. Technological advances have provided significant benefits to those tasked with keeping us safe while at the same time raising appropriate dialogue about how we can leverage those benefits while minimizing unwarranted intrusions on personal privacy.
Please note: this section refers to the SST ShotSpotter outdoor gunfire detection technology. Indoor sensors are entirely different and provide additional privacy protections.
ShotSpotter sensors are specifically designed to be triggered by loud explosive or “impulsive” sounds only. The entire system is intentionally designed not to permit “live listening” of any sort. Human voices do not trigger ShotSpotter sensors. There are many other loud noises that do not trigger ShotSpotter: car doors slamming, people yelling “bang bang!”, loud music, airplane engines, leaf blowers, cheering, highway noise, car engines revving, drag races or tires squealing.
In addition, sensors are intentionally deployed in elevated locations (typically 50-100 feet above street level on building rooftops, sometimes 30-40 feet above ground on a street pole) for three reasons:
1) to maximize their ability to “listen to the horizon” and thereby reduce the number of sensors required;
2) to minimize the background noise from cars and other street noises, thus also reducing the number of sensors required; and
3) to minimize the chance that a human voice will be intelligible, however briefly, in order to protect privacy.
ShotSpotter sensors do not use “high gain,” directional, or other specialized microphones.
The microphones themselves are similar to those in a mobile phone. When spoken outdoors at distances in excess of approximately 10 feet, a private conversation spoken in a normal voice is simply not intelligible to a human, to a mobile phone, or to ShotSpotter sensors. This is an intentional engineering and design choice made to ensure that ShotSpotter sensors cannot be used to monitor private conversations. It would be safe to say that an individual walking down the street and speaking into a mobile phone is more likely to unintentionally overhear and transmit the private conversation of someone else walking and talking nearby than that a ShotSpotter sensor, far further away, and only triggered by loud, impulsive noises, would be.
When a loud explosive noise triggers a sensor, it instantly sends summary data about the acoustic event (e.g. time stamp, sensor location, amplitude and envelope characteristics, etc. but explicitly not the audio of the sound itself) to a centralized processor at our SST-operated data center. There, if no other sensors trigger (i.e., if only one sensor hears the particular impulse), nothing else happens and no incident is created. If multiple sensors (usually 3 or more) report impulsive noises within a narrow time window which are sufficiently loud and mathematically consistent with their having originated at a single location, software algorithms attempt to calculate that origin location. If an accurate location can be determined, the associated sensors’ data are aggregated (again, without the audio) and an incident is “created” in a centralized database. A second filter then applies artificial intelligence and statistical techniques to attempt to identify what type of sound originated at this location based on the measurements of the sound. In most cases, the parameters of the sound permit the incident to be filtered out, because it is, e.g., a pile driver or a jackhammer. In a percentage of cases, the characteristics of the sound are consistent with an explosion (gunfire, firework mortar, firecracker, backfire, etc.). In those cases, and only in those cases, the sensors are permitted to push a small snippet of audio to our data center. Otherwise, the audio will be flushed from the sensor’s buffer and lost permanently. This is an intentional privacy-driven design: an active step must be taken only in the context of an explosive triggering acoustic event, or the audio is erased and overwritten.
In those cases in which an explosive triggering acoustic event is detected and located, the brief audio snippets are sent to SST’s Real Time Incident Review Center (IRC) for analysis and alert qualification by highly trained experts in gunshot acoustics. Within seconds, SST’s IRC sends those qualified gunfire alerts directly to a dispatch center, PSAP, patrol officers or other agencies for an effective, coordinated response. The gunfire alerts that the ShotSpotter system delivers to our police agency clients provide a digital record of violent gun crimes in progress, including minimally brief snippets of audio recordings of those crimes. For any given illegal gunfire incident, that snippet can only contain a few seconds of audio before the first shot and after the last shot. The purpose of these short seconds of audio on either end of the gunshots is to allow a human reviewing in the incident to clearly tell when the shooting starts and stops, including judges and juries during possible future criminal proceedings.
No Live Audio Streaming
As mentioned above, the entire system is intentionally designed not to allow “live listening” of any sort. There is no “listen” button available to law enforcement, or to the staff of our Incident Review Center, except the buttons which replay the specific few seconds of incident audio surrounding an impulse noise determined to likely have originated from an explosive source.
No Private Conversations
ShotSpotter sensors do not have the ability to listen to indoor conversations. They do not have the ability to overhear normal speech or conversations on public streets. Recently, privacy zealots have pointed to three extremely rare “edge cases” (3 out of approximately 3 million incidents detected in the past 10 years), in which a human voice yelling loudly in a public street at the scene of a gunfire incident was overheard for a very brief period (a few seconds). They have inaccurately assumed that ShotSpotter sensors are constantly transmitting audio streams, or somehow have been reconfigured to listen to private conversations. That simply isn’t true. In one of these three cases, only two words were overheard; in the others, a sentence was heard before the gunshot and in the other a similar number of words were heard immediately after a gun shot. In all cases, the words were yelled loudly, in a public place, at the scene of a gunfire-related crime, and within a few seconds of that event.
Policy and Security Minutiae
If you are still with us, here are some additional details: All servers and software used to process, store and protect data are managed and maintained by SST. Police agencies subscribe to the hosted service on an annual basis, radically streamlining the cost and complexity of using gunfire alert and analysis to enhance awareness, response and community safety. SST owns these data and does not release to anyone other than the customers under contract and according to the terms of that contract, thus further ensuring the safety and security of the data. Customers do not have administrative access to our servers, software, sensors, or any other means to circumvent SST’s security and privacy measures.
SST has taken appropriate security approaches to prevent anyone or any entity from gaining unauthorized access to our systems including our processors, networks or sensors. In addition to the fact that the system is designed not to permit live streaming audio, even if an intruder were to take control of our data center and network, they could not “make” a sensor deployed in the field stream audio. It simply isn’t possible: the sensors operate on a proprietary protocol and intentionally do not contain code which permits them to stream audio. Asymmetric key encryption is used to control access to sensors, and SST employees are required to use dual-factor authentication to gain access to most critical systems.
In the event that the ShotSpotter system fails to detect an incident, it is SST’s policy only to respond to requests for incident data or audio related to specific, verified gunfire incidents. In no event does incident audio extend beyond 2 seconds before and 4 seconds after an incident.
In addition to all of these technical and security measures taken to protect privacy and prevent misuse, SST has adopted a human resources policy to ensure that employees and contractors adhere to our privacy policies.
In the end, we believe that the privacy of our citizens and the community and social benefits of decreased gun violence are not at odds with each other. Our ultimate goal is to ensure that both are satisfied. We believe we have taken all reasonable and necessary precautions to assure a robust and strong privacy posture. We will continue to review, revise—and strengthen if necessary—these policies.
Methodology and Notes
1. The data in this Index is taken only from the areas covered by Shotspotter systems. There is no assurance that conclusions drawn from this data will be valid outside the coverage areas.
2. The 2016 analysis in this report is based on 82 communities that had Shotspotter Flex coverage (reviewed alerts) and were collecting data as of December 31, 2016. Of these, 72 were used in providing data for 2016 gunfire, and 59 were used in comparing 2015 to 2016.
3. In order to perform an apples-to-apples comparison of gunfire rates per square mile for 2015 and 2016, only those 59 communities that had Flex coverage for more than 4/5 of the non-holiday portion of the year in both 2015 and 2016 are used in the comparison. Furthermore, only those incidents within the coverages areas as of the beginning of 2015 were used in comparing gunfire rates for 2015 vs. 2016. Any coverage areas and incidents in those areas that were added after the beginning of 2015 were ignored in the comparison. However, the added coverage areas were included for the analysis of 2016-only data.
4. Some communities were not covered during some parts of 2015 or 2016. Therefore, when calculating values such as gunfire incidents per square mile, care must be taken to account for the different number of days of coverage for different communities. The chosen solution was to impute the number of gunfire incidents for those days for which there was no coverage, taking into account known information about incident rates for the community, the day of the year, the day of the week, and the year. This method is like proration, but is more accurate. Imputation of incident data for a year is done only for communities that have coverage data for more than 4/5 of the non-holiday portion of that year.
This method was cross-checked using cities with two full years of data, comparing actual data to imputed values for simulated missing values. The average difference by city between the gunfire rates using imputed values vs. using actual values was only 2.2%, showing that imputation can be relied on to give accurate results.
5. Gunfire incidents for a year period were counted if the local time in the time zone of their occurrence was between 00:00:00 standard time (i.e., midnight) on January 1 and 23:59:59 on December 31st (i.e., 1 second before midnight on January 1).
6. Incidents during the holiday periods of New Years and 4th of July are not counted in the statistics unless explicitly noted because of the prevalence of celebratory gunfire and fireworks during those holiday periods and the fact that they are highly inconsistent with the normal patterns. The holiday periods are January 1, 2014; June 12, 2015 through July 12, 2015; December 30, 2015 through January 4, 2016; June 24, 2016 through July 15, 2016.
In addition, some cities had other days near the holiday periods with exceptionally large volumes of celebratory gunfire and fireworks. The gunfire data for these days were not used, but were filled in by imputation. The total number of these days is very small.
7. Communities without at least 20 incidents in all of 2015 were not used when comparing gunfire rates.
8. Incidents were counted only after formal qualification and operational use of ShotSpotter data by the client agency began, even if gunfire or other incidents were detected previously. Incidents were counted as gunfire if they were classified as Single Gunshot, Multiple Gunshot, or Possible Gunfire by SST-certified review personnel. All other incident types (fireworks, firecrackers, explosions unrelated to gunfire, transformer explosions, thunder, lightning, helicopters, etc.) were excluded from all statistics presented in this report. Gunfire incidents not reviewed by SST-certified review personnel are also excluded.
ShotSpotter data does not remain static, as information and adjustments are often made several days or weeks after initial detection (as forensic evidence is analyzed, cases are investigated, etc.). This report takes into account the most accurate and recently-available information.
9. Square mileage is measured on the basis of contractual coverage area. For each such area, the geographic area is defined as a polygon surrounding each coverage area. In some cases, small areas within these coverage areas are intentionally excluded when gunfire is regularly expected in those specific locations (e.g. a legal outdoor shooting range or police practice range). In those cases, gunfire which takes place in those locations outside of authorized areas is still included in the tallies, but gunfire which takes place during permitted (expected) periods is not included.
10. When the Friday, Saturday and Sunday gunfire totals are compared to the rest of the week, a day is defined as starting at 06:00:00 local time and extending to 05:59:59 the next morning. For example, early 02:05 Sunday morning is counted as Saturday night.
11. Individual hours of the week and days of the week were calculated on a local time basis.
ShotSpotter Gunfire Index Release – 2017
SHOTSPOTTER REPORTS NEARLY 75,000 PUBLISHED GUNFIRE INCIDENTS IN U.S. CITIES
MONITORED IN 2016, COMPARED TO 54,699 IN 2015
Gunfire Detection Leader’s Data Shows Busiest Day of Gunfire in 2016 with 85 Live Gunfire Incidents on August 14
NEWARK, Calif. – April 26, 2017
ShotSpotter, Inc., the global leader in gunfire detection and location technology, today announced that among U.S. cities using ShotSpotter technology, published gunfire incidents* reached a total of 74,916 for 2016, compared to 54,699 in 2015. As part of its ShotSpotter 2016 National Gunfire Index, the report also found that the single busiest day for a city was 85 gunfire incidents, on August 14. The highest number of gunshots in a single hour was 26 gunfire incidents on August 13, between 10:00 PM and 11:00 PM.
The ShotSpotter 2016 National Gunfire Index is based on data from a statistical sample of U.S. cities that used ShotSpotter in 2016. The 72 cities that were analyzed had a total coverage area of 305.0 square miles, with a median coverage area of 3.1 square miles.
ShotSpotter’s National Gunfire Index delivers objective urban gunfire incident data that clearly demonstrates gun violence in the U.S. is much greater than what is typically measured in terms of homicides and non-fatal shootings alone. Findings for 2016 include:
• 74,916 ShotSpotter published incidents of gunfire in the U.S.
• Oct. 23 was the busiest day of gunfire for total ShotSpotter published* alerts
, with 339 gunfire incidents reported
• Busiest hour of gunfire for total ShotSpotter published alerts
– 56 published gunfire incidents on August 28, 2:00AM to 3:00 AM
• Busiest day of gunfire – by City
- 85 published gunfire incidents on August 14
• Busiest hour of gunfire – by City
- 26 published gunfire incidents on August 13, 10:00 PM to 11:00 PM
• 2016 rate of gunfire per square mile in city areas covered by ShotSpotter
o Minimum = 4.3
o Median = 103.8
o Maximum = 1,214.8
• Average number of rounds per reported incident - 3.8
o Northeast 3.3 rounds per incident (2015, 3.2 rounds)
o Midwest 3.6 rounds per incident (2015, 3.7 rounds)
o South 3.7 rounds per incident (2015, 3.6 rounds)
o West 4.3 rounds per incident (2015, 4.2 rounds)
o Caribbean 6.3 rounds per incident (2015, 5.4 rounds)
• Single incident with largest round of gunfire
- 65 published gunfire incidents on December 3
“With such a significant number of ShotSpotter published gunfire incidents in the past year, it’s clear to see that urban gunfire continues to be a challenge for many communities across the United States,” said ShotSpotter President and CEO Ralph A. Clark. “But knowledge is power, and we believe the local agencies’ understanding and use of this data is critical in enabling them to partner with communities in reducing gun violence and improving the safety of residents.”
HOW SHOTSPOTTER WORKS
ShotSpotter uses sophisticated acoustic sensors to detect, locate and alert law enforcement agencies of illegal gunfire incidents in real time. The acoustic sensors are strategically placed in an array of 15-20 sensors per square mile in order to reliably detect and accurately triangulate gunshot activity. Each sensor captures the precise time and location associated with boom and bang sounds (impulsive noise) that may represent a gunshot. This data is first filtered by machine algorithms that are then further qualified by expertly-trained staff in the 24x7 Incident Review Center (IRC) at ShotSpotter, to ensure the events are in fact gunfire. This process takes less than 45 seconds, between the actual shooting and the pushed digital alert, which includes a precise location on a map (latitude/longitude) with corresponding meta data such as the address, number of rounds fired, type of gunfire, etc. delivered to any browser-enabled device or mobile device. Utilizing the gunfire audio clip, and tactical information, officers can approach the precise location of the gunfire incident quickly and safely to engage the shooter, interview witnesses, and collect key evidence at the crime scene.
= the total number of gunfire incidents detected by ShotSpotter solutions alerts that were sent to law enforcement agencies.
ShotSpotter® Flex℠ helps local law enforcement agencies detect gunfire accurately, protect officers with increased tactical awareness, and connect the police to the community while also connecting police to their mission to serve and protect. With the precise location of illegal gunfire incidents, first responders can more quickly aid victims, collect evidence, and identify, investigate and ultimately apprehend armed, dangerous serial shooters.
ABOUT SST, INC.
ShotSpotter is the leader in gunshot detection solutions that helps law enforcement officials and security personnel identify, locate and deter gun violence. Our public safety solution, ShotSpotter Flex, is deployed in urban, high-crime areas to help identify, locate and deter gun violence by accurately detecting and locating gunshots and sending real-time alerts to law enforcement. Our security solutions, SST SecureCampus and ShotSpotter SiteSecure, are designed to help law enforcement and security personnel serving universities, corporate campuses and key infrastructure and transportation centers mitigate risk and enhance security by quickly notifying authorities and first responders of an active-shooter. The speed and accuracy of our solutions enable rapid response by enforcement and security personnel, increase the chances of apprehending the shooter, aid in evidentiary collection and serve as an overall deterrent. ShotSpotter solutions are installed in more than 90 locations across the United States. More information can be found at www.ShotSpotter.com
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Liz Einbinder +1 (415) 577-8255 leinbinder@ShotSpotter.com