Acoustic gunshot location in complex environments: concepts and results
Robert L. Showen, Robert B. Calhoun, Wai C. Chu, Jason Dunham · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2008
A gunshot location system can be implemented in complex urban environments using a distributed array of acoustic sensors. A primary difficulty in computing the source location is that unknown path obstructions in the environment interfere with the reception of the sound at the sensor, by blocking the sound entirely, by refracting the path, or by creating echoes. Other complications are created by the similarity between gunshot sounds and other less interesting urban noises, frequency-dependent absorption of sound, and possible computational difficulty when multiple gunshots generate large data sets that stress real-time analysis routines. The ShotSpotter Gunshot Location System®1, deployed in over two dozen cities in the United States, detects and locates gunfire using a network of acoustic sensors placed on rooftops and utility poles, on moving vehicles, or on personnel. This sensor network, combined with a software system to collate and compute location results from the array of sensors, accurately locates gunshot sounds in complex urban environments. A classifier discards solutions incorporating non-gunshot audio pulses produced by the complex environment. Examples of difficult detection problems, including gunshots from a moving source, show that the detection and classification algorithms described are effective at recovering useful results from signals found in real-world urban scenarios.