Submitted to the Senate Hearing on ‘Excessive Noise from Wind Farms’ Bill, 14 November 2012.
Based on the results of the study it is argued that, when exposed to wind farm noise and wind turbine generated air pressure variations, some individuals will more likely than not be so affected that there is a known risk of serious harm (also termed ‘significant adverse effect’) to health. By ‘serious harm’ it is meant harm that is more than mere annoyance and that can be quantified in terms of reported illness, sleep disturbance or other physical effect. Definitions of ‘serious harm’ are postulated:
- A measure of serious harm is if the exposed individual is adversely affected to the extent that he or she is obliged to remove himself or herself from the exposure in order to mitigate the harm; and / or
- A measure of serious harm is if three or more serious adverse health effects are recorded for an individual. Three serious adverse health effects are established from this study as being:
- sleep disturbance with a global PSQI greater than 5,
- a state of constant anxiety, anger and helplessness,
- an SF36v2 mental health value of less than 40. …
The measures of wind turbine noise exposure that the study has identified as being acoustical markers for excessive noise and known risk of serious harm to health (significant adverse health effects) are:
- Criterion: An LAeq or ‘F’ sound level of 32 dB(A) or above over any 10 minute interval, outside;
- Criterion: An LAeq or ‘F’ sound level of 22 dB(A) or above over any 10 minute interval inside a dwelling with windows open or closed.
- Criterion: Measured sound levels shall not exhibit unreasonable or excessive modulation (‘fluctuation’).
- Criterion: An audible sound level is modulating when measured by the A-weighted LAeq or ‘F’ time-weighting at 8 to 10 discrete samples/second and (a) the amplitude of peak to trough variation or (b) if the third octave or narrow band characteristics exhibit a peak to trough variation that exceeds the following criteria on a regularly varying basis: 2dB exceedance is negligible, 4dB exceedance is unreasonable and 6dB exceedance is excessive.
- Criterion: A low frequency sound and infrasound is modulating when measured by the Z- weighted LZeq or ‘F’ time-weighting at 8 to 10 discrete samples/second and (a) the amplitude of peak to trough variation or (b) if the third octave or narrow band characteristics exhibit a peak to trough variation that exceeds the following criteria on a regularly varying basis: 2dB exceedance is negligible, 4dB exceedance is unreasonable and 6dB exceedance is excessive.
- Definitions: ‘LAeq’ means the A-weighted equivalent-continuous sound pressure level; ‘F’ time-weighting has the meaning under IEC 61672-1 and ref. 18; “regularly varying” is where the sound exceeds the criterion for 10% or more of the measurement time interval of 10 minutes; and Z-weighting has the meaning under AS IEC 61672.1 with a lower limit of 0.5Hz.
- Approval authorities and regulators should set wind farm noise compliance levels at least 5 dB(A) below the sound levels in criterion (1) and criterion (2) above. The compliance levels then become the criteria for unreasonable noise.
Measures (1-6) above are appropriate for a ‘noise’ assessment by visual display and level comparison. Investigation of health effects and the complex nature of wind turbine noise require the more detailed perceptual measures of sound character such as audibility, loudness, fluctuation strength, and dissonance.
Download original document: “Wind Farm–Generated Noise and Adverse Health Effects”
This article is the work of the author(s) indicated. Any opinions expressed in it are not necessarily those of National Wind Watch.
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