As other elementary schools across the country were preparing for the new school year by cleaning classrooms and training teachers, Hermosa Elementary, in Artesia, New Mexico was installing a network of wireless microphones that could pick up the specific concussive audio signature of gunfire. Placed high in classrooms and hallways, the golf-ball-sized devices can alert authorities to the sound and location of gunshots, reportedly within 20 seconds of firing. They can also identify make and model of guns, and automatically lock doors and sound alarms throughout the campus.