For the past decade or so, Police Departments across the country have been implementing new forms gunfire locating technology. ShotSpotter is the primary developer of these technologies. In many urban areas, Police Departments are setting up audio sensors capable of pinpointing the sound of gunfire. They typically place about 15 to 25 of these per square mile. They are “always listening” type devices that start recording once they detect a gunshot. The technology filters out background noise and uses an algorithm to determine what soundwaves could potentially be a gunshot.