Near-field acoustic holography and non-negative intensity for prediciton of sound radiation
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Date
2015Author
Liu, Daipei
Havranek, Zdensk
Peters, Herwig
Marburg, Steffen
Kessissoglou, Nicole
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Temperature inversion and wind conditions are known to have a significant effect on noise propagation over long distances. Consideration of such conditions is a challenging part of assessing environmental noise propagation over several kilometres in environments with relatively low background noise levels. To consider these phenomena, noise consultants generally use standard commercial noise models, which apply correction factors, linear vertical approximations of the prevailing weather conditions, or assume horizontally uniform weather conditions. These assumptions, whilst not ideally reflective of real-world weather conditions will produce generally reliable assessments of noise overall, but for any specific period, these assumptions may lead to inaccurate assessments of short term noise levels. This is especially the case when there are significant spatial or temporal changes in the wind direction, wind speed or temperature in the period under consideration. As a result, the assumptions underpinning commercial noise models are not well suited to real-time or predictive/forecast management of short term noise impacts over long distances. Understanding the nature of these non-linear, time and space varying weather conditions can lead to more accurate noise assessments. Examples of temperature profile measurements and new techniques to consider these influences in a three dimensional time and space varying field are outlined, including predictive/forecasting noise modelling for management of industrial noise levels.