The IEI 510 is a patented passive sonic glass break detector designed to detect the sound signals produced by breaking glass, including 1/8″ and ¼” plate glass and ¼” wired glass. The Tri-Gard features patented signal processing which analyzes all three dimensions of sound, these being Amplitude (loudness), Frequency (tone or pitch) and Rate of Rise in time the signals “amplitude” and/or the “Rate of Change” in time frequency. The ATL (Automatic Tracking Level) allows the Tri-Gard to self adjust to compensate for background noise and/or rising audio signals.