Showing posts with label noise. Show all posts
Showing posts with label noise. Show all posts

March 23, 2017

Letter in support of proposed wind turbine sound rules

To the Clerk of the Vermont Public Service Board:

I support the proposed wind turbine sound rules as a first step to protect the aural environment of our mountains.

As you know, a quiet rural night in Vermont is likely to have a sound level of only 25 dBA or even less. An increase in ambient noise of 5 dB is recognized as a cause of widespread complaints. So limiting the sound level at night to 35 dBA is not severe but actually rather lenient.

The proposed rule does not address low-frequency noise, which Denmark (the world's leader in wind energy technology and implementation) since 2011 has limited to 20 dBA indoors (10-160 Hz).

Infrasound (which is not heard but instead felt) is also a concern, with many acoustic engineers determining that a C-weighted indoor limit of 50 dB is necessary to protect health.

Nor does the proposed rule address amplitude modulation, the distinct "swish" or "thump" of large wind turbines. In the UK, planning permission for the Den Brook project included a rule to limit amplitude modulation: A 125-ms pulse of 3 dBA or greater (3 dB being the difference in noise level detectable by the human ear) can not occur in any 2-second period five or more times in six or more minutes of any hour, when those minute-long average noise levels are 28 dBA or more.

While these limits, as well as the proposed setback of 10 times the total height from residences (which should be at least 15 times the height, and from property lines, so that people can enjoy all of their property), begin to protect human neighbors, they do nothing to protect the wildlife of the mountains, who in most cases are much more sensitive to sound than humans.

[See also:  Proposal and comments for implementing a rule regarding sound from wind generation projects, by Stephen Ambrose]

November 16, 2014

Wind Turbines and Health: A Critical Review of a Critical Review of the Scientific Literature

J Occup Environ Med. 2014 Nov;56(11):e108-30. Robert J. McCunney, MD, MPH, Kenneth A. Mundt, PhD, W. David Colby, MD, Robert Dobie, MD, Kenneth Kaliski, BE, PE, and Mark Blais, PsyD

Objective: This review examines the literature related to health effects of wind turbines. Methods: We reviewed literature related to sound measurements near turbines, epidemiological and experimental studies, and factors associated with annoyance. Results: (1) Infrasound sound near wind turbines does not exceed audibility thresholds. (2) Epidemiological studies have shown associations between living near wind turbines and annoyance. (3) Infrasound and low-frequency sound do not present unique health risks. (4) Annoyance seems more strongly related to individual characteristics than noise from turbines. Discussion: Further areas of inquiry include enhanced noise characterization, analysis of predicted noise values contrasted with measured levels postinstallation, longitudinal assessments of health pre- and postinstallation, experimental studies in which subjects are “blinded” to the presence or absence of infrasound, and enhanced measurement techniques to evaluate annoyance.


Brief critique by Eric Rosenbloom:

“The Canadian Wind Energy Association (CanWEA) funded this project ....” McCunney and Colby had already prepared a similar review for the American and Canadian Wind Energy Associations (which are industry lobby groups) in 2009.

The paper consistently implies that the inaudibility of infrasound makes it nonproblematic, but by definition infrasound is inaudible and there is a substantial body of research showing that it is indeed harmful. The review ignores conference papers and so bypasses the issue of measurable infrasound inside homes as well as the unique characteristics of wind turbine noise as presented by many acousticians.

In its assessment of epidemiologic studies, the review rigorously critiques those that correlate wind turbine proximity and health problems while accepting without question those that find no such correlation (for example, a Polish study by industry consultants). In all cases that attempt to correlate complaints with noise levels, the latter are only estimated and characterized as continuous dBA tones. The paper picks out for special praise surveys that set out to prove “psychogenic” causes of health problems, which could not be more biased. This section concludes with a warning against the “mistaking of correlation with causation”, which only underscores the authors’ desperation to dismiss health problems as pre-existing and to ignore the consistent evidence that those health problems disappear when people move away or spend time away from the wind turbines (which they would no doubt only view as more evidence that they are indeed psychogenic, as if people willingly suffer physically in their homes but not when they are forced to abandon them). And again, they insist on the quotidian nature of wind turbine noise as being no different from ocean waves or air conditioning, ignoring the ever-growing documentation that it is indeed unique, and uniquely disturbing to many. As with other complaints, the review dismisses sleep disturbance as a fault of the sufferer, not the giant wind turbine thumping away all night. This bias is simply repeated in the next section that examines – and dismisses concerns about – infrasound and low-frequency noise. Again, the paper even denies that any infrasound and/or low-frequency noise (let alone that from wind turbines) can affect health, despite decades of research showing otherwise.

Continuing in this vein, the review of annoyance (a health effect according to the World Health Organization) examines only efforts to show it to be due only to the complainant’s psychology, not actual noise. The review unsurprisingly gives pride of place to the “nocebo” theory that nonsensically blames complaints on the publicity of them.

In its conclusion, the review cites the World Health Organization’s Night Noise Guidelines as a non sequitur vindication that wind turbine noise is not a problem, but fails to note that those guidelines specify an outside limit of 30 dB, which no jurisdiction on earth enforces, let alone regulation of amplitude modulation and infrasound, or even adequate setback distances, all of which the wind power industry fiercely fights (eg). The review itself makes no siting or regulatory recommendations (which might harm the industry paying for this review), instead placing the entire blame for problems on those who suffer them. A shameful performance.