9/17/2023 0 Comments Noise soaker pacific sound control![]() ![]() ![]() Propagation over even longer ranges (up to 2000 km) has been measured using explosive detonations as sound sources empirical results ( Whitaker, 1995) and Parabolic Equation (PE) simulation ( Le Pichon et al., 2012) have shown that infrasound pressure levels from such sources involve mechanisms (e.g., stratospheric ducting and wind perturbations) that are not important for the distances that wind turbine noise propagates. There are also a number of observations of favorable propagation (i.e., less attenuation, or the sound energy is channeled so that there is a longer distance propagation) of wind turbine noise over water (e.g., Sondergaard and Plovsing, 2005 Boue, 2007 Johansson, 2003). Observations have also been made during high winds in the daytime to a distance of 20 km downwind ( Willshire, 1985 Willshire and Zorumski, 1987 Hubbard and Shepherd, 1991). Under specific conditions, wind turbine infrasound noise has been measured during stable, or very stable atmospheric conditions (e.g., during a temperature inversion at night) at distances of 4 km ( Hansen et al., 2015 Zajamšek et al., 2016) and up to 90 km ( Marcillo et al., 2015). FFP calculations would be recommended for large distances, when there are large numbers of wind turbines, or when investigating specific meteorological classes. Both measurements and FFP calculations showed that beyond 1 km, ISO based calculations could underestimate sound pressure levels. This suggests that ISO 9613-2 (1996) could be an effective screening method. In the Health Canada study, to a distance of 4.5 km, long term average FFP calculations were highly correlated with the ISO based calculations. For comparison, infrasound propagation was also estimated using ISO 9613-2 (1996) calculations for 63 Hz. Since onsite meteorology was not available for the Health Canada study, PE and FFP calculations used Harmonoise weather classes and field measurements of wind turbine infrasound to estimate yearly averaged sound pressure levels. These measurements, combined with onsite meteorology, were in agreement with calculations using Parabolic Equation (PE) and Fast Field Program (FFP). In field measurements, spectral peaks were identifiable for distances up to 10 km away from wind turbines at frequencies from 0.5 to 70 Hz. ![]() This study was developed to estimate wind turbine low frequency and infrasound levels at 1238 dwellings in Health Canada's Community Noise and Health Study. ![]()
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