Abstract: Methods and apparatuses are described herein. In an example embodiment, a glass-break detector is provided. Glass-break detector includes a speaker and a microphone in sound communication with the glass and is configured to perform an echo signature procedure to generate a baseline echo signature. The echo signature procedure includes: causing the speaker to transmit an ultrasonic signal onto the surface of the glass, causing the microphone to measure sound wave amplitudes on the surface of the glass, and generating an echo signature based on the sound wave amplitudes. Glass-break detector is configured to repeat the echo signature procedure to generate a test echo signature and detect a break in the glass based at least on the baseline echo signature and the test echo signature.