1. THE VERY BASIC SCIENCE OF SOUND
[BE:
Whenever solid, liquid or gaseous molecules move in contact with one another,
(as a rock falling down a mountain side), by the force of a blow, (such as
striking a bell), rushing air, (as through your vocal cords in speech or song),
running water, (as in rapids), an electric current, (as in your sound system’s
speakers), etc., etc., vibrations of those objects are created. These
vibrations spread out from their source into the medium around them, whether
air, water, or solid, and are transmitted as “pressure waves”, losing energy
over distance until they decrease in height, (amplitude or loudness), and are,
in essence, expired. The higher the waves are, the louder the
sound. Closely spaced waves, that is, those of a “short wavelength”, create
high pitches or frequencies, such as those from the high notes on a
piano. Those with longer wavelengths create low frequencies, such as
those on the low notes of a piano.
All
such pressure waves are often referred to as “sound”, though humans “hear” only
a narrow range of their frequencies. We all know of dog whistles
that have a higher frequency, (higher pitch), than we can hear, but dogs, bats,
and many other animals can hear them. We can hear frequencies of pressure
waves lower than those from the lowest piano keys, but elephants and whales,
for example, emit and hear frequencies that are much lower in pitch and that
travel great distances, (miles!), through air or water, allowing long-distance
communication among members of each species. But our ears cannot “hear”
these “sounds”.
For
common understanding and study, the whole spectrum of “sound pressure waves”
has been divided into several groups of different frequencies, (lengths of the
waves). All of these waves cause vibrations in any type of matter they
encounter, solid, liquid or gas, including our bodies. For this
discussion, I’ll focus on the two groups of most concern to us regarding wind
turbine noise, dBA and dBC.
We
measure sound in units called “decibels”, abbreviated “dB”. The “pressure
waves” which humans can actually “hear” are labeled dBA. Pressure waves
of lower frequency than our ears can “hear” are called “infrasound” and are
labeled dBC. Each group of frequencies, (dBA or dBC) can be measured
separately, but only by screening out the other groups. So for the
purposes of understanding how these two ranges of “sound pressure” affect
humans, basic sound meters have separate settings to read dBA or dBC, but not
both at the same time.
Infrasound wavelengths, dBC, though inaudible to us, still “register”, (vibrate), in our ears and other parts of our bodies where they create most of the health issues caused by wind turbine noise. Immediately below are two letters from camp owners on the north shore of Concord Pond in Woodstock, about two miles from the Spruce Mountain Turbines. The first describes the annoyance and property value issues of dBA pressure waves, and the second deals more with the health effects of dBC.
*************
Date: 09/20/2012 11:04 AM
A Woodstock Property Owner and Concord Pond Resident
************
The Sound Study equipment is still on the shore of the Pond, and we've heard no responses or calls from anyone about its results. The blood noise I mention above is what happens at night. I wake up and my head aches and is pounding. I had one night that the pain was so bad I could not lift my head from the pillow. My husband and I compared notes and it feels like our blood pressure/pulse are reverberating in our heads in sync with the towers. This weekend the windows were closed because it was cold and the noise was not as loud, but I still woke up every hour or so with the pounding. [BE: though the dBA was quieter, the closed windows do not shut out the dBC.] I’m hoping to find time to read some articles on wind turbine syndrome. We also spend more time at our camp than nearly anyone else on the pond. That may be why we are more in tune to them.
Prior to the last few weeks it was loud only on random days. Since Labor Day (or thereabouts) it seems to be 24/7 every weekend. The wind is obviously more prominent now. We think we just had such a hot, quiet summer that it was not happening that often. All visitors have noticed and said that it may be below the requirements, but that it not something that they could live with. We have tried to keep an open mind and see if we can live with it, but after the last three weekends it doesn't bode well.
We are devastated. We are currently in the process of selling our house [BE: in southern Maine] - - on the market two days and already have an offer! So we will not make any decisions yet as we need to wait until we are resettled.
I know this is the emotional part, but this was our dream. We have had a tough life and the last few years have been good to us, so we were able to buy a camp and help make a dream come true. We searched for two years for something we could afford, and we have been so happy there. We know we will not get what we paid for it 5 years ago, let alone the money we have put into it structurally. When we purchased it the front porch was totally rotten, there was no outhouse and the camp was falling over. We have put our hearts and souls into this and still had so many plans. We had hoped to live there six months of the year starting in 2013.
A Couple on Concord Pond
E-mail any questions or suggestions to: bpwindcomm@oxfordnetworks.net
Infrasound wavelengths, dBC, though inaudible to us, still “register”, (vibrate), in our ears and other parts of our bodies where they create most of the health issues caused by wind turbine noise. Immediately below are two letters from camp owners on the north shore of Concord Pond in Woodstock, about two miles from the Spruce Mountain Turbines. The first describes the annoyance and property value issues of dBA pressure waves, and the second deals more with the health effects of dBC.
*************
Date: 09/20/2012 11:04 AM
To: <bpwindcomm@oxfordnetworks.net>
Subject: RE: SMW Noise Test
Dear Committee:
Noise at Concord Pond was awful Saturday the 15th and seems to be getting worse with the climate change and foliage drop. My wife and I have decided that we will ready the camp for sale as it is obvious that we will no longer enjoy the serenity of the pond. We do not see the towers from our camp and thought we had dodged a bullet - how untrue. We sit on the deck and start to read a book or do some studying and low and behold the wind changes and the sound of the towers breaks our solitude.
I am truly saddened by the fact that the project was allowed to be sighted where it is and hope that the town of Woodstock and DEP officials realize that if they allow the project to expand that it will affect others elsewhere in town. Maybe it will be one of them next time! I wish this on no one and am happy for the townspeople who say they can't hear them or they are not bothered by them. I wish I were one of them.
I can only hold to the great many memories since first coming here in the early 50's and wish the rest of Woodstock the best in the future with whatever they decide. I cannot have a vote as I am not a resident. Time to move on.
Best wishes –
************
Date: 09/20/2012 06:16 AM
Subject: RE: SMW Noise Test
I called the SMW hot line again this last weekend. It has been awful. We believe that now it is September and the winds are more prominent, we may be hearing them, [BE: the turbines], a bit more like they would normally be prior to the quieter spell of the previous two or three weeks. If that is the case, I don't see how we will survive. My husband is hearing it at night now and understands the blood, [BE: pulse], sounds in our heads while trying to sleep.
I called the SMW hot line again this last weekend. It has been awful. We believe that now it is September and the winds are more prominent, we may be hearing them, [BE: the turbines], a bit more like they would normally be prior to the quieter spell of the previous two or three weeks. If that is the case, I don't see how we will survive. My husband is hearing it at night now and understands the blood, [BE: pulse], sounds in our heads while trying to sleep.
The Sound Study equipment is still on the shore of the Pond, and we've heard no responses or calls from anyone about its results. The blood noise I mention above is what happens at night. I wake up and my head aches and is pounding. I had one night that the pain was so bad I could not lift my head from the pillow. My husband and I compared notes and it feels like our blood pressure/pulse are reverberating in our heads in sync with the towers. This weekend the windows were closed because it was cold and the noise was not as loud, but I still woke up every hour or so with the pounding. [BE: though the dBA was quieter, the closed windows do not shut out the dBC.] I’m hoping to find time to read some articles on wind turbine syndrome. We also spend more time at our camp than nearly anyone else on the pond. That may be why we are more in tune to them.
Prior to the last few weeks it was loud only on random days. Since Labor Day (or thereabouts) it seems to be 24/7 every weekend. The wind is obviously more prominent now. We think we just had such a hot, quiet summer that it was not happening that often. All visitors have noticed and said that it may be below the requirements, but that it not something that they could live with. We have tried to keep an open mind and see if we can live with it, but after the last three weekends it doesn't bode well.
We are devastated. We are currently in the process of selling our house [BE: in southern Maine] - - on the market two days and already have an offer! So we will not make any decisions yet as we need to wait until we are resettled.
I know this is the emotional part, but this was our dream. We have had a tough life and the last few years have been good to us, so we were able to buy a camp and help make a dream come true. We searched for two years for something we could afford, and we have been so happy there. We know we will not get what we paid for it 5 years ago, let alone the money we have put into it structurally. When we purchased it the front porch was totally rotten, there was no outhouse and the camp was falling over. We have put our hearts and souls into this and still had so many plans. We had hoped to live there six months of the year starting in 2013.
A Couple on Concord Pond
************
There are lots more letters in the, "Woodstock Comments and Complaints", tab at the top of the homepage of: http://woodstockwindordinance.blogspot.com/
E-mail any questions or suggestions to: bpwindcomm@oxfordnetworks.net
2. PEACE OF MIND
[BE:
By “peace of mind”, I mean the following phenomenon, illustrated in the graph
below. When people in a “quiet rural community” are exposed to noise that
is frequent and/or somewhat long-lasting, the louder it is, the higher
percentage of the people hearing it will complain of being “highly annoyed” by
the noise.
In
the graph below, I suggest not getting lost in the fine print but noting that
the horizontal axis represents increasing noise from left to right; the
vertical axis represents, from bottom to top, the increasing percentage of
people within hearing distance, (which is a larger group as the noise increases
and travels further), who are “highly annoyed”.
The “Graph”, below is © 2O13 by Acoustical Engineers Robert Rand of Brunswick, ME, and Steven E. Ambrose, of Windham, ME, both members of INCE, (The Institute of Noise Control Engineers).
3. “THE ‘HOW TO’ GUIDE TO SITING WIND
TURBINES TO PREVENT
HEALTH RISKS FROM SOUND”
By: Acoustical Engineers George
W. Kamperman, P.E. and Richard R. James, INCE. [BE: PE” (Professional Engineer), “INCE” (The Institute of
Noise Control Engineers)]
[BE:
This paper was researched and written by two of the country’s pre-eminent
Acoustical Engineers. This is my condensed version of the 47 page
original in order to get to the heart of the conclusions of the authors without
wading through the details of the research. The “Table” at the bottom of
the page was published by the World Health Organization in the 1970s.
Kamperman and James, and other acoustical experts, researched and confirmed
these limits as needed for human health and peace of mind, and the
International Organization of Standardization, (ISO), adopted it in the early
1990s. In the late’ ‘90s the numbering system of the ISO’s standards was
changed and the table redone as a typed paragraph of the same information in a
different numbered section, but I include the original table here for its
brevity and clarity. Mr. James gave us permission on 8/28/12 to share this
condensation as an accurate summation of the conclusions of the complete paper
at the URL below.]
"A subset of society should not be forced to
bear the cost of a benefit for the larger society.” 1.
1. George
S. Hawkins, Esq., “One-Page Takings Summary: U.S. Constitution and :\Local Land
Use”, Stony Brook-Millstone Watershed Association; “…nor shall private property be taken for
public use, without just compensation.”
Fifth Amendment, US Constitution
[ BE: I take the
quote from Hawkins to mean that the people who live where Industrial Wind
Turbines have been sited too close, (and hopefully that's not a large number),
should not have to bear the annoyance and dangers to their health that the
majority of residents, who live at a safer distance, do not have to bear.]
Industrial
scale wind turbines are just beginning operation in the U.S. Their
presence will increase dramatically over the next few years given the push by
the Federal and state governments to promote renewable energy sources through
tax incentives and other forms of economic and political support. States and
local governments in the U.S. are promoting what appear to be lenient rules for
how industrial wind farms can be located in communities, which are
predominantly rural and often very quiet.
Studies
already completed and currently in progress describe significant health effects
associated with living in the vicinity of industrial grade wind turbines. This
paper reviews sound studies conducted by consultants for governments, the wind
turbine owner, or the local residents for a number of sites with known health
or annoyance problems. The purpose is to determine if a set of simple
guidelines using dBA and dBC sound levels can serve as the ‘safe’ siting
guidelines.
Discussion
After
reviewing the materials in numerous scientific studies, we have arrived at our
current understanding of wind turbine noise and its impact on the host
community and its residents. The review showed that some residents living as
far as 2 miles from a wind farm complain of sleep disturbance from the noise.
Many residents living one-tenth this distance, 1000 feet, from a wind farm are
experiencing major sleep disruption and other serious medical problems from
nighttime wind turbine noise. The peculiar acoustic characteristics of wind
turbine noise emissions cause the sounds heard at the receiving properties to
be more annoying and troublesome than the more familiar noise from traffic and
industrial factories. Limits used for these other community noise sources do
not appear to be appropriate for siting industrial wind turbines.
Proposed
Sound Limits
We are proposing to use the commonly accepted dBA criteria for
the audible sounds from wind turbines. In addition, to address the lower
frequencies, we propose to add limits based on dBC.
|
[
BE: This illustrates that the State DEP and the new “revised” version of
the Bethel ordinance are using standards that are “reasonable” for “Urban Mixed
Residential/Industrial” communities, while what is “reasonable” for quiet rural
communities like Bethel and Greenwood is 35 dBA, 30 dBA and 25 dBA.
So it’s clear that the people who are saying that 45 and 50 dBA are
"reasonable" for our towns have no idea what they’re talking about!]
E-mail any questions or suggestions to: bpwindcomm@oxfordnetworks.net
E-mail any questions or suggestions to: bpwindcomm@oxfordnetworks.net
4. SETBACKS
[BE: This is my
summary off four scenarios, based on proposals for the Greenwood Wind Project
and Spruce Mountain Wind, using an Excel table which was shared with us by
Robert Rand. He is the acoustical expert who co-produced the graph,
above, showing how the percentage of “highly annoyed” people increases as noise
levels increase. This Excel table contains a formula for figuring out the
setback distance to achieve an intended noise level.
I
have demonstrated how this table works to the Bethel and Greenwood Wind
Ordinance Committees, but I can’t figure out how to include a working Excel
table on this site. I would be happy to demonstrate it at the Public
Hearing in Bethel on October 30. If your group would like a
demonstration, E-mail me at the address on the homepage of this blog .
Let’s do it before voting on Bethel’s revised ordinance!
When
you put numbers for, “How Loud Is Each Turbine”, “How Many Turbines There Are”,
and “The Maximum Allowed dBA Level At A Non-Participating Property Boundary”,
(which is the intended noise level), into the table, the formula gives you the
appropriate setback in feet and miles for that scenario!
My
entire experience with these issues over the past six years convinces me that
the reasonable maximum dBA in quiet rural communities like ours are those
recommended in the WHO/ISO table, above. In the examples below, for safe
and tolerable sound levels, I use the WHO/ISO evening level of 30 dBA.
My first example of the Excel table uses a maximum allowable dBA level of 55 dBA, which are the limits of the Maine DEP and the revised Bethel Ordinance. For the Greenwood project, Calpine said at the first public meeting I attended, at the Legion Hall on Gore Rd. last summer, that they would use 17-19 turbines, each producing 105 - 110 dBA. They have since said they might use only 13 turbines. I'll use Calpine’s numbers of 105 dBA as the noise of each turbine, (which is also the noise produced by the Woodstock turbines), and 17 turbines with the first example, then change the numbers to give you different scenarios.
My first example of the Excel table uses a maximum allowable dBA level of 55 dBA, which are the limits of the Maine DEP and the revised Bethel Ordinance. For the Greenwood project, Calpine said at the first public meeting I attended, at the Legion Hall on Gore Rd. last summer, that they would use 17-19 turbines, each producing 105 - 110 dBA. They have since said they might use only 13 turbines. I'll use Calpine’s numbers of 105 dBA as the noise of each turbine, (which is also the noise produced by the Woodstock turbines), and 17 turbines with the first example, then change the numbers to give you different scenarios.
“Setbacks: The Distance it takes for Turbine
Noise to
Deteriorate to an Intended Maximum Level”
Deteriorate to an Intended Maximum Level”
The
intended maximum noise level in this first example may be
"reasonable" for Bath Iron Works and the Portland docks, but not for
our towns. For quiet Rural Communities, the "intended" safe setback distances of the ISO table of 35 dBA daytime, 30 dBA evening, and 25 dBA at night, must be used:
The first scenario shows what the Greenwood proposal would be with State rules:
How Loud is each Turbine: 105 dBA
How Many
Turbines: 17
Maximum allowed dBA: 55 dBA Setback: 1,178 feet, or 0.22 miles.
This means that they would be allowed to make 55 dBA at .22 mi. from your house, where you could be exposed to 55 dBA.
Maximum allowed dBA: 55 dBA Setback: 1,178 feet, or 0.22 miles.
This means that they would be allowed to make 55 dBA at .22 mi. from your house, where you could be exposed to 55 dBA.
The
second scenario shows the "reasonable", (safe, ISO Recommended), setback for the Greenwood turbines, used above:
How Loud is each Turbine: 105 dBA
How Loud is each Turbine: 105 dBA
How Many
Turbines: 17
Maximum allowed dBA: 30
dBA Setback:
20,945 feet, or 3.97 miles.
The safe limit would require the turbines to be 3.97 mi from your house, where you would be exposed to only 30 dBA.
The safe limit would require the turbines to be 3.97 mi from your house, where you would be exposed to only 30 dBA.
The
third scenario is Woodstock's reality today, and Bethel's future if the revisions are approved on Nov. 13. Note how the number of
turbines makes little difference in the setback distance, compared to the first
scenario. (And see the paragraph below):
How Loud is each Turbine: 105 dBA
How Loud is each Turbine: 105 dBA
How Many
Turbines: 9
Maximum allowed dBA: 55 dBA Setback: 1,037 feet, or 0.20 miles.
This means that the turbines could be sited .2 mi. from your house and you could be exposed to 55 dBA.
Maximum allowed dBA: 55 dBA Setback: 1,037 feet, or 0.20 miles.
This means that the turbines could be sited .2 mi. from your house and you could be exposed to 55 dBA.
The
fourth scenario shows Woodstock with a (safe, ISO recommended), setback:
How Loud is each Turbine: 105 dBA
How Many Turbines: 9
How Loud is each Turbine: 105 dBA
How Many Turbines: 9
Maximum allowed dBA: 30 dBA
Setback: 18,444 feet, or 3.49 miles.
This scenario shows the "reasonable" and safe numbers for
Woodstock. If Patriot had sited their wind farm at least 3.5 miles from
where people live, no one would be complaining there. But they didn't
have to do that under the State regulations, so a lot of residents are paying
the price in annoyance and ill-health effects.
I include these to illustrate that there is no shortcut to setback. Siting industrial wind turbines closer and louder than is recommended by the WHO and ISO, (the Table at the bottom of, "The 'How To' Guide to Siting Wind Turbines", above), jeopardizes human health and peace of mind. Thank you for joining the effort to decide what’s reasonable.
If you have the courage and time, and if you haven't yet done so, PLEASE go to the tab for, “Woodstock Comments and Complaints", at the top of the homepage of this site and read more of the letters from people who live within one to three miles of Patriot Renewables Spruce Mountain Turbines.]
I include these to illustrate that there is no shortcut to setback. Siting industrial wind turbines closer and louder than is recommended by the WHO and ISO, (the Table at the bottom of, "The 'How To' Guide to Siting Wind Turbines", above), jeopardizes human health and peace of mind. Thank you for joining the effort to decide what’s reasonable.
5. INFRASOUND: THE HAZARDS TO HEALTH
(Optional)
(Optional)
[
BE: Infrasound wavelengths, though inaudible to us, still “register”,
(vibrate), in our ears and other parts of our bodies where they create most of
the health issues caused by wind turbine noise. This piece describes in detail
their effects on humans. You will get a better view of the illustration in
the article, which did not download here, by going to the full article on-line
at the URL just below the title. But all
the text is here. If you go to the web article, I ask you not to get lost
in the description of the illustration, but focus on the rest of the paper
which describes the health dangers, causes and effects. You might also
read Dr. Salt’s letter rebutting one of the Wind Industry’s “false” truths at:
http://www.epaw.org/documents/Alec_Salt_to_Martii_Warpenius_18Sep2013.pdf ]
http://www.epaw.org/documents/Alec_Salt_to_Martii_Warpenius_18Sep2013.pdf ]
WIND TURBINES CAN BE HAZARDOUS
TO HUMAN HEALTH
My new Lab webpage (including the latest version
of our Cochlear Fluids Simulator) can be found at: http://otocore.wustl.edu/saltlab/
Washington
University in St. Louis
Large wind turbines generate very low frequency sounds and
infrasound (below 20 Hz) when the wind driving them is turbulent. The amount of
infrasound depends on many factors, including the turbine manufacturer, wind
speed, power output, local topography, and the presence of nearby turbines
(increasing when the wake from one turbine enters the blades of another). The
infrasound cannot be heard and is unrelated to the loudness of the sound that
you hear. Infrasound can only be measured with a sound level meter capable of
detecting it (and not using the A-weighted scale). Video cameras and other
recording devices are not sensitive to infrasound and do not reproduce it.
You cannot hear the infrasound at the levels generated by wind
turbines, but your ears certainly detect and respond to it. The picture at left
shows the enormous electrical potentials that infrasound generates in the ear.
The potentials (18.7 mV pk/pk amplitude in this case) are about 4 times the
amplitude of sounds in the normal frequency range that are heard. These measurements
show that the low frequency part of the ear is extremely sensitive to
infrasound.
Our measurements show the ear is most sensitive to infrasound when
other, audible sounds are at low levels or absent. That is why homes and
pillows probably contribute to the problem. To clarify, maximum
stimulation of the ear with infrasound will occur inside your home, because the
audible sound of the turbines is blocked by the walls of the house, but
infrasound easily passes through any tiny openings. Similarly, sleeping
with one ear on a pillow will block audible sound to that ear but will not
block the infrasound. In either case, the infrasound will be strongly
stimulating the ear even though you will be sleeping not be able to hear it.
The presence of sounds at higher frequencies, in the range of 150 Hz 1500
Hz range at levels above 60 dB SPL, suppresses the ear's response to
infrasound. It may be possible to mask the influence of infrasound with other
noises, but frequency properties of the masking noise must be
considered. Frequencies above about 1500 Hz will not do anything to help.
We know that the ear is being stimulated by this sound pressure,
but why would that matter if you cannot hear it? There are several ways
that infrasound could affect you even though you cannot hear it. They are:
1. Causing Amplitude
Modulation (pulsation) of heard sounds.
We know that infrasound affects the sensory cells of the ear in a
way that changes their sensitivity (like turning the volume control of the
stereo up and down repeatedly). This is a biological form of amplitude
modulation that cannot be measured with a sound level meter. The people who are
measuring amplitude modulation of heard sounds with sound meters are looking at
something completely different. Biological amplitude modulation can be much
more powerful, with the volume cycling from going from “off” to “full”, rather
than just changing a few dB. So, to investigate amplitude modulation without
considering the infrasound - induced component is probably not going to explain
the true nature of the problem. Symptoms: Pulsation,
annoyance, stress.
2. Stimulating
“subconscious” pathways.
We know that activity in many nerves of the ear does not result in
“hearing”. If the nerves from the utricle or semi-circular canals are
stimulated, you may get eye movements and changes in tension of neck muscles,
but you don't hear it. The pathway of conscious hearing is very well
established. It goes from the inner hair cells of the cochlea, through type I
auditory nerve fibers, to the fusiform cells of the cochlear nucleus in the
brain, and so on. This pathway has been well-studied. The outer hair cells of
the ear (the ones that are sensitive to infrasound) do not connect to this
conscious pathway. They connect to the type II nerves (which make up 5% of the
nerve fibers), then to granule cells in the brain, then to cartwheel cells and
to a host of other pathways in the brain. The cartwheel cells are known to be
inhibitory to hearing which may explain why the stimulation is not heard. It is
known that granule cells are connected into circuits related to attention and
alerting. It is not unreasonable to think that stimulation of this pathway
could wake you up, and you wouldn't even hear what had actually woken
you. Symptoms: Sleep disturbance, panic, with chronic sleep
deprivation leading to blood pressure elevation, memory dysfunction and more.
3. Causing Endolymphatic
Hydrops.
The endolymph is a fluid filled compartment in the ear, like a
balloon, surrounded by delicate membranes. In some conditions, such as in
people with Meniere's disease, a swelling of this compartment occurs. These
patients suffer from repeated vertigo spells, fluctuating low frequency hearing
loss, tinnitus and a sensation of fullness or pressure in the ear. Low
frequency sounds, at levels that are not damaging and do not affect hearing,
have been shown to cause endolymphatic hydrops. This can occur quickly, but
also recovers quickly so there are minimal consequences. This effect has been
demonstrated with tones as low as 50 Hz, but has never been studied with lower
sound frequencies or with infrasound. There is no reason to believe that lower
frequency sounds will not generate hydrops, as we know that endolymphatic
responses to infrasound are larger than those to heard sounds. As hydrops
develops, endolymph moves and expands the weakest part of the balloon, which is
the saccule. The saccule is the body's gravity receptor, so if it is disturbed
you will feel “off balance”, dizzy (subjective vertigo) and nauseous,
especially if only one ear is affected (maybe the one you had on the pillow? -
see above). Studies so far have only studied this for brief exposures of a few
minutes. Effects are likely to increase with prolonged exposure to the sound.
Furthermore, when the endolymphatic hydrops reaches a degree where the
helicotrema of the cochlea is occluded, this makes the ear about 20 dB more
sensitive to the low frequency sound and will undoubtedly exacerbate the
problem. Symptoms: Unsteadiness, disequilibrium, vertigo,
nausea, (“seasickness”), tinnitus, sensation of pressure or fullness in the ear
4. Possibly Potentiating
Noise-Induced Hearing Loss
Animals were exposed to damaging noise, with and without low
frequency sound present. When very low frequency sound was present, animals had
greater hearing losses and larger areas of hair cell loss. So, if you are doing
anything noisy (mowing the yard, using a chainsaw) the damage to your ears
could be greater if low frequency or infrasound levels are high. It is
therefore important to wear hearing protection when pursuing noisy pastimes
near sources of infrasound (that you can't even hear). As a side-note, hearing
protectors, especially the over-the-ear cup type, will not protect against
infrasound even though they do reduce the audible, damaging sounds you can
hear.
Each of the above mechanisms is based on published data showing the
phenomenon exists, thus making it a scientifically plausible process. No one
has shown that any of these four mechanisms cannot occur. However, the degree
to which each phenomenon occurs in humans following prolonged exposure to the
infrasound from wind turbines has not yet been demonstrated. But each now needs
to be studied in more detail. The potential symptoms they could generate in
people seem quite familiar though.
The Wind Turbine Industry is generally dismissive of claims that
wind turbines can affect human health. For example, Scott Smith, vice president
of policy for CanWEA (the Canadian Wind Energy Association), referring to the
report of the Chatham-Kent Tribunal (Spring 2011) stated, “The wind energy
industry welcomes the tribunal’s decision, as it is consistent with the balance
of expert scientific and medical information which clearly indicates there is
no direct link between wind turbines and effects on human health”.
This dismissive statement fails to recognize a conclusion of the
Chatham-Kent tribunal, specifically “This case has successfully shown that
the debate should not be simplified to one about whether wind turbines can
cause harm to humans. The evidence presented to the Tribunal demonstrates that
they can, if facilities are placed too close to residents. The debate has now
evolved to one of degree.” We agree that the effects of wind turbine
noise on humans are largely unexplored and more research is needed. We are
convinced that infrasound levels generated by some large wind turbines are
unusual in the environment and that there have been no systematic long-term
studies of prolonged exposure to such sounds on humans or other animals.
The wind industry has taken the position that if you cannot hear
the infrasound, then it cannot affect you. As you can see above, we disagree
strongly based on our understanding of how the ear works. These web pages
consider in more detail some of the areas that we have expertise.
[ BE: The article above seems to have been published in
2013; today’s longer blades do not seem to considerably affect dBA, but they do
rotate slower than earlier shorter blades and do create more and lower
frequency-infrasound, (dBC).]
