SoundOff, a system unveiled by researchers from Georgia Tech, introduces ultra‑low‑cost passive ultrasound tags that sit on everyday objects—door knobs, faucets, cabinets—and emit inaudible pulses when moved. The tags require no power or circuitry, letting a wearable receiver decode distinct ultrasonic signatures and map interactions to smart‑home actions in real time, enabling seamless automation without extra hardware across smart environments.

Through extensive tests, the team showed that each tag’s waveform remains distinguishable even amid background noise. A physics‑based design engine can generate thousands of unique geometries, each producing a signature that a machine‑learning classifier can recognize with over 90 % accuracy. The open‑source pipeline supplies CAD files and a Python script for rapid prototyping in any indoor space without complex installations.

Deploying SoundOff turns ordinary rooms into sensor‑rich environments without cameras, microphones, or batteries. Potential uses span elder‑care monitoring, automated home notifications, and industrial workflow tracking. By removing privacy‑raising sensors and reducing setup costs, the system offers a scalable, low‑friction path to smarter living and working spaces for residents and businesses that value security and efficiency without intrusive hardware installations today.