Shooter Alarm System in Enclosed Spaces

James Candy | 23-FS-057

Project Overview

Multiple shootings have occurred in a variety of environments ranging from shopping malls, military bases, concerts, and most unnerving children's schools. Active shooter detection/localization/tracking in an enclosed environment is a daunting problem from a physics-based perspective. Using acoustics in such a scenario leads to a wide variety of complications especially due to multiple paths that the sound waves can undertake as well as distortions created by a large variety of obstructions and extraneous noise sources in enclosed spaces. This effort focused on developing a low-cost system to solve the shooter problem as an alarm/communication mechanism as well as a stand-alone local system capable of alerting the facility and the in-coming authorities.

The objective was to determine the feasibility of a low-cost, novel sensor capable of detecting the presence of a shooter in an enclosed space (e.g. school) for direct notification to first responders. The sensor "fuses" critical information about the underlying gunshot phenomenology of sound, vibration and light propagation in a highly reverberant, enclosed space with a potential multitude of extraneous disturbances (speech, book drops, fire alarms, etc.). To ascertain feasibility two major characteristics must be achieved: (1) reliable detection of a gunshot(s); and (2) minimal susceptibility to disturbances (false alarms). Our approach to achieve a reliable detection  was to incorporate certain "features" that uniquely identify a gunshot to be extracted from the sensor measurements: (1) sound intensity (sound pressure level (SPL):110-160 decibels); (2) gunshot duration (3-5milliseconds); (3) light flash intensity (0.8-3microseconds); and (4) vibration response (g-forces).

After a judicious review of these critical gunshot features and component sensors, we established a set of specifications and selected a set of low-cost (<25 $) sensors (accelerometers (vibrations), microphones (intensity), infrared (light)). Small ensembles of data were collected and analyzed ensuring potential gunshot detection with the low-cost sensor suite was highly successful. I stole the end of the sentence/paragraph from their technical report (kathryn)

Thus, the feasibility of a cost-effective, embedded, Shooter Alarm System (SAS) sensor enables each of these gunshot features to be measured, processed and extracted enabling a reliable (detection), effective (timely), economic (low-cost) solution to the shooter problem in enclosed spaces.

Mission Impact

Other government agencies have expressed keen interest and are potential users/participants, including the Federal Bureau of Investigation and the Department of Justice. Lawrence Livermore National Laboratory will be able to lead in this area due to the previous work on acoustic communications that have demonstrated/published/patented this technology for related secure communication problems. We expect new patents and collaborations will evolve for this problem and have a huge impact across the nation. 

Publications, Presentations, and Patents

Fisher, K. A., Candy, J. V., Bower, D. E., Shooter Alarm System: Processing & Development, IPO Presentation, 2020. 

Candy, J. V., Fisher, K. A., Candy, C. R., Localization Based on Time-Reversed Event Sounds, U.S. Patent 11,495,243 B2, Nov. 8, 2022.

Candy, J. V., Fisher, K. A., Candy, C. R., Event Detection Unit, U.S. Patent 11,538,322 B22, Dec. 27, 2022.