Wind turbine audibility calculations inside dwellings.

The objective of the current paper was to characterize indoor wind turbine sound pressure levels (SPLs) to assess the audibility of wind turbine noise indoors, accounting for window opening, frequency spectra, and presbycusis. Loudspeaker generated noise was used to determine the outdoor to indoor SPL differences at 11 representative dwellings using ISO 140-5:1998. The procedure was extended to 16 Hz. With windows closed, indoor broadband A- and C-weighted SPLs were lower by 25.9 and 15.3 dB, respectively, for wind turbine noise spectra. With windows opened, the corresponding results were 13.8 and 9.9 dB, respectively. Standard deviations for these results were 3 dB so that indoor and outdoor SPL would tend to be highly correlated. For 35 dBA outdoor SPL, the indoor SPL was potentially audible at frequencies as low as 31.5 Hz. Specifically, at 35 dBA, 80% to 100% of adults below the age of 60 years, would potentially be able to hear wind turbine noise indoors with windows partially open. This would drop to 10% to 30% with closed windows. Uncertainties around these estimates are discussed.