Critical responses to AAAC position statement on wind farms
The Association of Australian Acoustical Consultants has adopted the following position statement in relation to noise generated by wind farms. (link)
- Unlike other industrial noise sources, the noise level emitted by wind turbines is a function of wind speed. However, as the wind speed increases, noise from wind passing through vegetation also increases which can mask the noise from wind turbines. The noise criteria for wind farms applied in Australia establish fixed noise limits for low background noise environments and variable noise limits when background noise levels are higher. The applicable standards and guidelines incorporate appropriate methods to assess wind farm noise against the specified limits.
- “A” frequency weighted sound levels from wind farms can be reliably predicted. The prediction methods applied in Australia have been validated by extensive measurement studies.
- Infrasound (frequencies below 20Hz for the purpose of this statement) is generated by both natural sources (such as people, wind, waves, thunder and earthquakes) and mechanical sources (such as fossil fuel power generation, travelling in a car with windows open, traffic, industry, air conditioners, aircraft and wind turbines). Investigations have found that infrasound levels around wind farms are no higher than levels measured at other locations where people live, work and sleep. Those investigations conclude that infrasound levels adjacent to wind farms are below the threshold of perception and below currently accepted limits set for infrasound. The AAAC encourages members to continue to contribute to new research and review research in the technical literature.
- Amplitude modulation (which is a variation in the emitted noise level) is a fundamental characteristic of wind turbine noise and is a characteristic which is taken into account in the objective criteria specifically developed for wind farms. A higher than usual level of amplitude modulation has been reported to occur for brief periods at a small number of wind farm sites in other countries. AAAC members will continue to contribute to new research and review research in the technical literature.
- Some wind turbines may produce tones that are audible at residences under specific wind conditions. Objective assessment of the annoyance of tonality is well developed and its consideration is included in the assessment of wind farm noise in most Australian jurisdictions.
AAAC members should continue to primarily rely on the view of government bodies in relation to the health effects of wind farms and should conduct assessments in accordance with the relevant guidelines in each state.
To Martti Warpenius, Chairman, AAAC:
I am stunned that someone who professes to be an expert in acoustics could state something so misleading as “People themselves generate infrasound through things like their own heartbeat, through breathing and these levels of infrasound can be substantially higher than an external noise source.” (link)
Stimulation of the ear occurs not directly by pressure (which is why deep sea divers can still hear) but by induced motions of the inner ear fluids, which in turn move sensory tissues and motion-sensitive cells.
What you fail to understand is that when low frequency and infrasound enters the ear via the stapes, it causes fluid movements throughout the entire ear between the stapes in the vestibule, through scala vestibuli and scala tympani to the compliant round window membrane at the base of scala tympani. It is these fluid movements that drive sensory tissue movements and cause stimulation.
In contrast, pressure fluctuations generated by the body, such as by heartbeat and respiration, enter the ear via the cochlear aqueduct, not through the stapes. The cochlear aqueduct enters the ear adjacent to the round window membrane in the very basal part of scala tympani, so the fluid flows are localized in this tiny region of the ear. As the rest of the ear is bounded by a bony shell which is not compliant, fluid flows in the rest of the ear are substantially lower so that displacements of sensory tissues are negligible. Infrasound generated by the body, because it enters through the aqueduct, therefore does not cause stimulation of the ear. If you don’t understand the anatomy of the ear or this brief explanation, please refer to our paper, Salt & Hullar, Hearing Res. 2010; 268:12; Figure 2. (link)
Experimentally, we know that when infrasonic stimuli are applied to the ear acoustically, via the ear canal and stapes, they generate large electrical responses (Salt et al. J Acoust Soc Am. 2013; 133:1561). (link) Yet the sizeable pressures (measurable within the cochlea in mmHg) associated with heartbeat and respiration do not generate significant electrical responses.
I think the time has come when engineers who apparently know little about the physiology of the ear should not be making pseudo-authoritative statements about physiological and clinical aspects of low frequency and infrasound stimulation. Your comments not only fail in their stated goal to “clear up any confusion over the health impact of wind farms”, they are simply false and imply that infrasound from external sources such as wind turbines has negligible consequences to people, when we know that is not true.
It is appalling that rather than trying to find the scientific basis and seek solutions to the problem of wind turbine infrasound, the Chairman of the AAAC is peddling misinformation in an attempt to misdirect those who trust their guidance.
In my view, your statements are so misleading they need to be retracted.
Alec N. Salt, Ph.D.
Professor
Department of Otolaryngology, School of Medicine
Washington University, St. Louis, Missouri
Dear Members of the AAAC Executive Committee:
Your recent release of your “Position Statement on Wind Farms” fails to identify the authors of this document, in the interests of transparency a precise disclosure of who they are and which acoustics firm they worked for would be advantageous or one could assume a conflict of interest has transpired in the preparation of this statement.
Already there are a few acousticians and firms in Australia that have left themselves wide open to litigation due to their failure to adequately predict the true adverse impact of industrial wind turbine developments, especially where people have had to leave their homes because of adverse health impacts.
Litigation is already underway in the USA where a noise consultant is being sued personally as well as his firm. (link)
It appears that the position statement does not into take account other research findings. So is the AAAC and its members just merely puppets of the wind industry and happy to make statements based on the industries demands and enticements.
I have recently conducted a follow-up survey at the Cullerin Range Wind Farm which clearly shows that people are being impacted out to 8km by noise and/or vibration. “91% of those that responded out to 8km are affected by noise and/or vibration which is affecting their sleep and health, and those very same residents have all made complaints. In the 20 residences there are 50 residents with a total of 49 being affected by sleep deprivation and other health impacts” (link).
IN ALL HONESTY DO YOU BELIEVE THAT THE AAAC’S “POSITION STATEMENT ON WIND FARMS” THAT YOU HAVE RELEASED IS ETHICAL?
Patina Schneider
Dear members of the AAAC Executive,
I note the position statement of the Association of Australian Acoustical Consultants “Position Statement on Wind Farms”. (link)
I would like to point out the following statements:
AAAC members assess environmental noise against objective criteria set by relevant authorities …
AAAC members should continue to primarily rely on the view of government bodies in relation to the health effects of wind farms and should conduct assessments in accordance with the relevant guidelines in each state.
These statements are undoubtedly a call for acoustical consultants to compromise their professional opinions and standing in favour of “objective criteria” set by authorities. In case you’re not aware (I hope you are), these same authorities do not set criteria to protect each member of the public, but simply a compromise between emitters of noise and surrounding residents who may nevertheless have their health and well-being compromised.
I also note the following statement in the above mentioned position statement, and some comments of the AAAC Chairman in an online ABC report:
Those investigations conclude that infrasound levels adjacent to wind farms are below the threshold of perception and below currently accepted limits set for infrasound. (AAAC position statement)
The Chairman of the AAAC, Martti Warpenius, says the group wants to clear up any confusion over the health impact of windfarms.
“People themselves generate infrasound through things like their own heartbeat, through breathing and these levels of infrasound can be substantially higher than an external noise source.” (ABC report)
I see no clarification over the health impacts from the AAAC – just analogies that add to the confusion. The surprising generalisation of perception and levels is profound – much in sync with the previous statements that direct members to narrowly defined “objective criteria”. There is no hint that given the widespread problems of noise around wind farm that these “objective criteria” need refining, perhaps redefining. And there is certainly no mention that AAAC members should primarily be furthering the cause of public health, particularly when they can see phenomena like amplitude modulation, noise nuisance, vibration, and psychosomatic symptoms destroying their client’s health!
I would like to point out two hypothetical scenarios that demonstrate how flawed the AAAC position is:
1) With reference to comparing equivalent noise levels: Someone tells a mother with post-natal depression that her crying baby is no louder than her radio, therefore she should perceive the crying as equally pleasant to her favourite music – clearly a dose of madness. So if someone around a wind farm can perceive an impulsive thump every second or so during sleep hours, we tell them to imagine they are enjoying themselves at the beach? They want to go to sleep, don’t they?
2) With reference to natural infrasound from the heart: Our guts are full of bacteria, digested food and excrement, but I see no one walking down the street stepping on dog poo and feeling it to be a minor inconvenience because they are full of … excrement.
Frankly, I think the position of the AAAC is utterly disgraceful, an attempt to bully members to tow the “official” line at the expense of professionalism, and demonstrates a keenness to protecting government and industry over the concerns, health and well-being of private citizens.
George Papadopoulos
Yass, New South Wales
To Tim Trewin, Secretary, AAAC:
Could you please inform me of the authors and contributors of this 'Position Statement', as well as the companies they work for and/or who employed them to prepare the statement, and/or who commissioned the statement, as you and they have neglected to include them in the statement?
If you are unable or unwilling to do so could you please ensure you notify everyone this statement was forwarded to that they are unwilling to have their names associated with it.
Could you also please explain why your organisation was willing to distribute this even though it does not provide references for papers published that contradict this statement.
Could you please also explain why your organisation is willing to allow some of its members to amongst other things:
not "provide professional opinions in an objective and truthful manner, avoiding statements that may be demeaning, misleading or unethical"
"knowingly omit from any finalised report any information that would materially alter the conclusion that could be drawn from the report"
That is, to violate these elements of your Code of Conduct. (link)
While existing noise guidelines are accepted by some authorities, it is now evident that these are insufficient to meet environmental requirements for a healthy human existence for some who report adverse health effects after Industrial Wind Turbines begin operating.
It is recognised and accepted that infrasound is dangerous to human health in other situations it is only a matter of time before full disclosure of the extent of the effects on human health of Industrial Wind Turbines is accepted by medical authorities.
It is not the role of acousticians to make medical diagnoses.
Acousticians around the world are conducting testing are various sites with differing conditions and have and are finding excessive noise is being emitted. These are FACTS, which the authors of this Statement are unwilling to accept.
It is up to your organisation to ensure that they do not cause unnecessary harm, the non disclosure of their names suggests they know they are being used by their clients to mislead people, and in assisting this your organisation in danger of being an accomplice.
J. A. Rovensky