Ambient noise definitions in municipal codes and the application of acoustical engineering

Abstract

The duration of a noise measurement period that is required to establish an ambient or background noise level can vary drastically, from minutes to years. The descriptor of ambient noise levels can also vary whether it is a time-average sound level (Leq), or an x-percentile-exceeded sound level (L50, L90) for a specified duration. None of the above methods are necessarily right or wrong, however some may be more or less appropriate depending on the sources of sounds that are sought to be regulated, the context of potential human impact, and the goals of the municipality. This session will present examples of ambient noise measurement procedures as informed by municipal code language, discuss the noise sources that are likely to exceed the respective ambient, and determine if the limits are appropriate, can be left to interpretation, or would require additional definition to properly represent conditions.