The aggression detector has been fitted to CCTV cameras on the streets of Groningen and Rotterdam in the Netherlands. In the U.K., London police also are considering installing the system, said Derek van der Vorst, the director of Sound Intelligence, the company that created the technology.
The system works by putting microphones in CCTV cameras to continually analyze the sound in the surrounding area. If aggressive tones are picked up, an alarm signal is automatically sent to the police, who can zoom in the camera to the location of the suspect sound and investigate the situation.
Everyday mutterings are not detected by the system, though, Vorst said. "You cannot push a button to hear what people are saying," he said. "And even if you could, the microphones are 3 to 4 meters above the ground, so the words cannot be heard