Entries in low frequency sound (1)
From Nova Scotia
INCREASING TURBINE NUMBERS COULD MEAN LARGER SETBACKS
By Cheryl LaRocque
Source: Amherst Daily News
July 19, 2012
AMHERST – For industrial wind turbines, low frequency sound emissions range: one person may not hear a noise a second person hears clearly, while a third person finds the noise loud and uncomfortable.
To date, some residents of Amherst and out of town visitors said: “I don’t hear them; the turbines don’t bother me; the turbines hum and/or drone and keep me awake at night; they gave me an ongoing migraine; they give me daily headaches; the turbines are noisy and I/we can’t sleep at night.”
Researchers explain individual hearing sensitivity varies greatly. If you are wondering why, the explanation may be tucked in the inner ear in a cluster of tiny, interconnected organs.
In an article published in the Bulletin of Science Technology & Society, 2011, Wind Turbines could Affect Humans, by Alec Salt and James A. Kaltenbach explained, wind turbines generate low-frequency sounds that affect the ear.
“The ear is superficially similar to a microphone, converting mechanical sound waves into electrical signals, but does this by complex physiologic processes.”
Serious misconceptions about low-frequency sound and the ear have resulted in a failure to consider how the ear works.
“Although the cells that provide hearing are insensitive to infrasound, other sensory cells in the ear are much more sensitive, which can be demonstrated by electrical recordings,” wrote Salt and Kaltenbach. “Responses to infrasound reach the brain through pathways that do not involve conscious hearing but instead may produce sensations of fullness, pressure or tinnitus, or have no sensation.”
There is overwhelming evidence large electricity-generating turbines cause serious health problems in a nontrivial fraction of residents living near them, explained Carl V. Phillips, MPP, PhD in his article Properly Interpreting the Epidemiologic Evidence About the Health Effects of Industrial Wind Turbines on Nearby Residents. The article was published in the Bulletin of Science Technology & Society (2011).
“These turbines produce noise in the audible and non-audible ranges, as well as optical flickering, and many people living near them have reported a collection of health effects that appear to be manifestations of a chronic stress reaction or something similar,” explained Phillips, a consultant and author specializing in epidemiology, science-based policy making and communicating scientific concepts to the public.
Dr. Robert McMurtry, former dean of medicine at the University of Western in London, Ont., published a case definition to facilitate a clinical diagnosis regarding adverse health effects and industrial wind turbines.
There is a move toward a safe setback of turbines of two kilometres from homes, explained Dr. John Harrison, physicist from Queen’s University in Kingston, Ont., in an email interview.
“In the absence of any independent studies of adverse health effects, a precautionary principle suggests all provinces and territories in Canada should adopt a two-km setback.”
Harrison’s expertise is in the properties of matter at low temperatures with emphasis on high frequency sound waves. For the past five years he has studied wind turbine noise and its regulation.
As the province of Nova Scotia continues to pursue and approve wind energy developments, it is important it take into account the larger the turbine and the increase in numbers of turbines would also mean an increase in setback distance, explained Richard R. James in a phone interview from his office in Okemos, Mich.
James is adjunct professor at Michigan State University and Central Michigan University with the department of communication disorders.
Richard R. James, INCE (Institute of Noise Control Engineering) is a certified noise control engineer and has been actively involved in the field of noise control since 1969, participating in and supervising research and engineering projects related to measurement and control of occupational and community noise for major US and Canadian Manufacturers. Since 2006, he has been involved with noise and health issues related to industrial wind turbines.
Other countries including Australia, Denmark, France, New Zealand and Germany have instituted strict regulatory requirements regarding industrial wind turbine setback or are in the process of tightening criteria that experience has shown are not protective. The Danish EPA (their regulatory body) recently instituted stricter regulations that require the turbine’s emission of low frequency sound be addressed.