United Co-op's trial of a white noise system to deter burglars has been so successful it plans to roll it out. White noise is created by an internal siren connected to the intruder alarm and when triggered the burglar is met by an unbearable barrier of sound. Warning signs are displayed in the stores. The system was introduced in March at four stores in Manchester which had suffered nearly 20 break-ins between them over two years. Since the trial began in March not a single burglary has occurred. The system will be installed at 60 stores which have suffered repeat burglaries, out of United's estate of 500. {{NEWS }}