Use of Long Term Monitoring Data for Defining Baseline Sound Levels

With the trend towards semi-permanent sound monitoring, and collection of ambient sound levels over long periods of time, the method used for processing these data become increasingly important when identifying baseline sound levels.When calculating a single figure for "typical" baseline ambient sound levels from long term data, a number of different analysis options are available, which can result in differing results. This, in turn, can have an influence on noise limits which may be set, for example to control noise from construction works, or for noise from new operations. This paper considers different methods for the calculation of typical sound levels from long term monitoring data and demonstrates both the importance of this choice and the variability which can result.Consideration is given to the implications on large infrastructure projects where it is desirable to use a single methodology for setting baseline ambient noise levels and agreeing these with numerous local authorities and other stakeholders.