Continuous, unattended noise monitoring systems can immediately alert you should noise levels exceed defined criteria. Once alerted to an exceedance, operators can act to return levels to compliance. This approach has two significant limitations. Firstly, the operator can only take action after the breach has occurred and therefore systems are only able to inform owners about problems that have occurred in the past, rather than allowing them to maintain compliance. Secondly, the noise limit exceedances might not be due to specific noise from the operator but from unrelated, residual noise in the often-complex noise climates around the particular site and will then be the cause for a false positive. Compliance breaches are frequently triggered by aircraft overflights, road traffic or community sources. Modern monitoring systems enable users to view noise characteristics and listen to the noise breach to determine the source and act if necessary. However, this approach can create a significant number of false positives each taking up operator time to address. A previous paper by the authors described how airport noise management systems have addressed this problem by combining data from other systems, and how different techniques are required in urban & industrial noise management. This paper describes developments in these techniques and gives examples of techniques that allow operators to take action before a compliance breach occurs, and to reduce the number of false positive alerts.
PACS no. 43.50.Rq, 43.50.Sr, 43.50.Yw