Miércoles 29 de Noviembre de 2006, Ip nº 181

Big brother is listening to you
Revellers planning a night out in the Netherlands this weekend should keep their voices down.

To prevent fights breaking out, surveillance cameras in the city of Groningen have been adapted to listen out for voices raised in anger. Microphones attached to the cameras feed the sound signals to software that can detect voices that are aggressive in tone. "Aggressive people tend to tense their larynx, and the sound made by their vocal cords is distorted," says Peter van Hengel of developer Sound Intelligence, a spin-off of the University of Groningen. This means that high frequency vowel sounds span a broader frequency range. "A truly aggressive voice is very hard to imitate," he says.

In a trial earlier this year, police made three arrests after being alerted by the system. Tests are also under way

  21/11/2006. New Scientist Magazine.