A2 Ambient Monitoring Adjustment
dBA Noise Consultants was involved in several A2 adjustment procedures over the years. The A2 adjustment to the Permissible Sound Level (PSL) is included in AUC “Rule 012” as well as AER “Directive 038” where the assumed Ambient Sound Level (ASL) according to table 1 in these documents is considered not representative of the actual soundscape. The A2 adjustment can be both positive and negative, increasing or decreasing the PSL by up to 10 dB. In two cases where the ambient sound level was dominated by traffic, an initial Comprehensive Sound Level (CSL) survey indicated that the unadjusted PSL was exceeded. Noise model calculations however indicated that the facilities themselves were compliant with the PSL. In both cases we measured the ASL in a 24 hour survey without the facilities operating, and compared those results to the results from a CSL survey. The comparison indicated compliance with the A2 adjusted PSL, confirming the conclusions from our modelling. Applications for an upwards A2 adjustment to the PSL were filed with the AUC and granted. See decisions 24897-D01-2019 from October 25, 2019, decision 24680-D01-2019 from August 23, 2019 and decision 22535-D01-2017 for details.