Subwoofer arrays are widely used in live sound events. However, the performance of sound systems and the generated environmental noise pollution in the vicinity of Roman theatres is not well researched and documented. The investigation aimed to determine the most suitable subwoofer array configuration for an outdoor Roman theatre according to their low frequency coverage across the audience area and overspill on nearby residential areas. Performance suitability was determined by measuring the overall sound pressure (dBA) and spectrum levels of the arrays within the audience area at several locations representative of nearby residential areas. The Array Performance Rating (APR) was calculated for each array configuration to complement performance assessments. Results showed a notorious difference between coupled and uncoupled arrays, as well as between ground-based and flown subwoofer configurations. It was proven that the flown point source array offered overall less sound pressure levels and spectral variability in the audience plane and it caused the least environmental noise pollution. The conclusions drawn from this study can provide valuable guidance applicable to future sound system deployments and reconstruction projects of ancient outdoor theatres of similar architectural and environmental characteristics.

Freight trains are a relevant source of environmental noise and require an acoustical assessment to quantify the exposure of the population using noise mapping. Once the results of the noise calculations have been developed, it might be necessary to adopt mitigation strategies that can be validated using these noise models. It is becoming increasingly common to undertake some form of validation exercise to cross-reference the calculated levels with measurements to reduce the uncertainty in the action planning. Based upon the results of the monitoring, the measured data may then be stratified regarding the source data and meteorological data and introduced into the calculation model, to enable the model to replicate the situation during the measurement windows (meta-models). The results from the calculations of each of these meta-models may then be compared with the noise measurement results as the basis for the validation study. This paper presents an overview of a verification project undertaken in South America where such a process was followed using the CNOSSOS-EU as the basis of comparison.