Page 25 - Volume 9, Issue 3

mood, cognitive functioning, and overall sense of
health and well-being.
5. There is insufficient evidence that the noise from
wind turbines is directly (i.e., independent from an effect on annoyance of sleep) causing health problems or disease.
6. Claims that infrasound from wind turbines directly impacts the vestibular system have not been demon- strated scientifically. Available evidence shows that the infrasound levels near wind turbines cannot impact the vestibular system.
a. The measured levels of infrasound produced by modern upwind wind turbines at distances as close as 68 m are well below that required for non-auditory perception (feeling of vibration in parts of the body, pressure in the chest, etc.).
b. If infrasound couples into structures, then people inside the structure could feel a vibra- tion. Such structural vibrations have been shown in other applications to lead to feelings of uneasiness and general annoyance. The measurements have shown no evidence of such coupling from modern upwind turbines. c. Seismic (ground-carried) measurements recorded near wind turbines and wind turbine farms are unlikely to couple into structures.
d. A possible coupling mechanism between infrasound and the vestibular system (via the Outer Hair Cells (OHC) in the inner ear) has been proposed but is not yet fully understood or sufficiently explained. Levels of infrasound near wind turbines have been shown to be high enough to be sensed by the OHC. However, evi- dence does not exist to demonstrate the influ- ence of wind turbine-generated infrasound on vestibular-mediated effects in the brain.
e. Limited evidence from rodent (rat) laborato- ry studies identifies short-lived biochemical alterations in cardiac and brain cells in response to short exposures to emissions at 16 Hz and 130 dB. These levels exceed measured infrasound levels from modern turbines by over 35 dB.
7. There is no evidence for a set of health effects, from exposure to wind turbines that could be characterized as a “Wind Turbine Syndrome.”
8. The strongest epidemiological study suggests that there is not an association between noise from wind turbines and measures of psychological distress or mental health problems. There were two smaller, weaker, studies: one did note an association, one did not. Therefore, we conclude the weight of the evi- dence suggests no association between noise from wind turbines and measures of psychological distress or mental health problems.
9. None of the limited epidemiological evidence reviewed suggests an association between noise from wind turbines and pain and stiffness, diabetes, high
blood pressure, tinnitus, hearing impairment, cardio-
vascular disease, and headache/migraine.
The study also recommended A-weighted sound levels based on World Health Organization data at night. It also recommended a comprehensive assessment of wind turbine noise in the Commonwealth based on IEC 61400-11. It is understandable that the reviewers took a “safe approach,” looking for incontrovertible evidence. The United States is in its relatively early stages with respect to identifying and understanding the causes of the individual problems experi-
enced by the near neighbors of these installations.
On October 23, 2011, in conjunction with this issue, Richard H. Campbell, FASA, FAES, NCAC of East Falmouth
wrote to the Falmouth Enterprise6:
I have been immersed in acoustics all of my pro-
fessional life. My experience includes noise control, performance halls, houses of worship and speech communication in noise. A disability has slowed me up in recent years but I have read nearly all of the reports and letters regarding Wind 1. Some of my colleagues have acted as consultants on this project and on occasion we have discussed the findings.
Fifty years ago there was not much known about quantifying hearing damage due to noise. A very large data collection process with intelligent analysis led Karl D. Kryter to author the seminal book synthesizing the subject, The Effects of Noise on Man. The first noise regulation in the US was in 1975 in Portland, Oregon. From then on noise became an environmental issue rather than just a “nuisance.”
Now we have a potentially serious noise prob- lem with Wind 1. An even larger problem we have as acoustic engineers is that there is no metric for evaluating disturbance due to infrasonic modulated noise – at least not yet. In fact there is not even an instrument that can accurately measure the radiat- ed acoustic and vibration field from slow-moving turbine blades. Falmouth is not alone as there is a lot of attention being paid to the problem in the UK, Canada and the EU.
The worst thing we can do is to ignore the affected people. They are a point on a curve yet to be drawn. Looking back at the history of hearing damage I can see many points shaping the curves we use to evaluate and predict industrial noise exposure. I personally delivered a hearing protector to a machinist who complained about the noise in an unforgettable way – his family life was coming apart. He agreed to wear them faithfully every time he ran the machine and a week later, after inter- viewing him again, I was astonished and pleased. Another point on the curve.
Noise regulations in effect now do not encom- pass turbine noise as a physiological or psychologi- cal disturbance. I see a statement that “ ... it does not violate the state regulation for environmental noise ...”. Okay, agreed. What instrument was used?
24 Acoustics Today, July 2013