PrivacyStreet microphones eavesdrop on crimes

Published 21 June 2010

The city of Coventry has installed microphones on street at the city center; the microphones detect suspect sounds, including trigger words spoken at normal volumes as well as angry or panicked exchanges before they become violent; operators can then direct police straight to the scene

Microphones that can detect aggression by the tone of someone’s voice were installed in Coventry, England, where they will cover an area blighted by drunken violence. The Coventry decision has raised the prospect of microphones coming to other cities in the United Kingdom.

The system, called Sigard, is able to direct CCTV cameras toward suspicious sounds, which can also be gunshots or the smashing of glass. Operators can then direct police straight to a confrontation, in the hope they can stop violence before it erupts.

The system was designed by mimicking the hearing processes of the human ear. It can filter out background noise. The microphones detect suspect sounds, including trigger words spoken at normal volumes as well as angry or panicked exchanges before they become violent.

Sound Intelligence, the Dutch company that manufactures the system, claims Sigard could be vital in combating violence on British streets. Privacy campaigners fear it may be used to record conversations and claim that Sigard is another milestone in Britain’s transformation into a surveillance society.

Sigard works by picking up the changes in someone’s speaking that are said to indicate violence is about to occur, such as a raised voice and change of tone. The Herald Scotland’s Jasper Hamill writes that last February, Sound Intelligence conducted a trial in Glasgow, installing microphones in the city center. At the time, company director Bram Kuipers said: “We detected aggression, and it’s currently under evaluation.”

He has suggested that police cars could be fitted with microphones and could cruise city centers, listening out for audible signs of trouble.

Sigard has also been tested in London, Manchester, and Birmingham. In Hackney in London, the system detected up to six crimes a night, including fights and guns being fired.

The microphones can hear from distances of 100 yards and can filter out background noise. They were installed in Coventry city center after a 9-month trial, and there are now seven microphones covering two streets.

Sigard systems are used more widely in Holland, where twelve cities have fitted the microphones and they are also in use on buses and trains.

The company stressed Sigard does not record conversations, but privacy campaigners fear it could used for this in the future.

The Sunday Times’s Kevin Dowling notes that other surveillance systems that have been tested can detect unusual or suspicious movements suggesting someone could be about to commit a crime. One, fitted to aircraft seat backs, can pick up on nervous expressions on the faces of passengers who may be terrorists.