Infrasound – the boomerang of the energy transition
People living in proximity to wind turbines often describe their complaints concerning low-frequency noise (infrasound) from these turbines as “I feel what you cannot hear”.
By Dr Thomas Carl Stiller, specialist physician of general medicine and cofounder of “Doctors for Emission Control” (AEFIS).
Translation from German by Friends Against Wind:
People living in proximity to wind turbines often describe their complaints concerning low-frequency noise (infrasound) from these turbines as “I feel what you cannot hear.” But what is the cause of infrasound, what impact does it have on people, what standards regulate the permissible sound emissions and what is the state of science on these issues? A “The Energy Question” contribution by Dr Thomas Carl Stiller.
Inaudible but biophysiologically effective sound is not science fiction but an increasing threat to health. First, a few physical bases: sound is the pressure change in a medium such as air and spreads around the source. The lower the frequency, the more sound is transported in the air. Very low frequencies are also transmitted through closed buildings. As a result of acoustic reflections and superimpositions, it can then lead to excessively high sound pressure values. In general, sounds and noises are described by frequency, timbre and volume.
The human ear can hear frequencies approximately in the range of 20,000 Hz, i.e., vibrations per second (high tones) to 20 Hz (low tones). The sound range above a frequency of 20,000 Hz is referred to as ultrasound, below 200 Hz as low-frequency sound, below 20 Hz as infrasound. Both infrasound and ultrasound are no longer perceived by the ear, but the body has a subtle perception for infrasound, and some people are particularly sensitive to low-frequency sound.
In nature, low-frequency vibrations are ubiquitous. For example, some migratory birds orient themselves by the noise of the sea which is transmitted over several hundred kilometres in the atmosphere. The sound pressure of natural noises in the infrasound range, however, is quite evenly distributed over the different frequencies and is not perceived as disturbing by humans. The infrasound from wind turbines is still measurable for several kilometres. (1)
On the other hand, humans are often exposed to technically generated infrasound in their immediate surroundings. In residential areas, in the age of energy efficiency regulations for new buildings, air heat pumps are increasingly used as energy sources, which are cheaper to purchase than many other heating systems. In operation, however, they are often annoying for the neighbours, if the compressors are too loud and run too long. Even more problematic are wind turbines, in particular the modern giant turbines, which are mostly placed in front of villages and settlements at a small distance from the housing development. A pressure wave is generated every time a rotor blade is passed in front of the tower; many people perceive this as periodic "thumping", sometimes also at a distance of several kilometres.
The consequences of technically generated infrasound are only gradually becoming understood. About 10 - 30 percent of the population is sensitive to infrasound radiation. These people, which in Germany number several million, develop numerous symptoms, which are now understood by more and more physicians. The low-frequency oscillations from compressors and wind turbines cause stress reactions in these people, which manifest themselves in sleep disorders, concentration disorders, nausea, tinnitus, dysphasia, dizziness, cardiac arrhythmia, fatigue, depression and anxiety disorders, earaches and permanent hearing impairments.
From a physiological point of view, there is damage to the hair cells of the cortical organ of the auditory canal and to permanent irritation in cerebral arteries, such as the amygdala (anxiety centre) (2). Effects on the heart and blood vessels included diseased changes of the connective tissue in the arteries of the pericardium (heart bag) detected in experiments (3) with animals which were exposed to infrasound for a long duration.
Those affected cannot escape the effects of health and harassment. They are often ineffective for a long period of time. A neurobiological habituation of sensitive persons on technical infrasound is not known. It is often falsely asserted that the symptoms are attributable to the attitude of persons concerned about the sources of the infrasound, and that a positive attitude towards the current energy policy so preserves them from infrasound symptoms. Unfortunately, this is not observed in medical practice; the symptoms are the same for all sensitive people. Numerous international studies have been carried out over the last few years, but in Germany this research is still very little developed and almost unknown at the political level.
If the symptoms occur, however, those affected are often hardly in a position to react. Those who live in a residential area affected by low-frequency noise and infrasound radiation cannot usually move away easily if, for example, they have to sell their house, which has lost a lot of value due to nearby wind turbines.
Who can perform optimally in today's working world if sleep deprived and unable to find peace and quiet in their home by pervasive infrasound loading. (4) How long can those affected compensate for this healthily and financially? Infrasound-sensitive people are ensnared in a tragic dilemma: their complaints are not taken seriously and legally they do not go further because of the lack of emission control regulations.
The acoustician Steven Cooper, together with a wind farm operator in Australia, investigated the effects of infrasound on the local population. Local residents in the vicinity of a nearby wind park complained about the above symptoms. But they did not have the wind farm directly in front of them. Cooper had their symptoms recorded at an exact time and checked the correlation with the activity of the wind turbines; the symptoms were strongest when the wind turbines were particularly active. (5)
In Denmark, information on malformed foetuses and miscarriages on a mink farm where wind turbines were subsequently built, as well as frequent reports of disease symptoms of people near wind turbines, led to a moratorium on wind energy expansion, pending completion of investigation of the connections. Also in Germany, the issue of infrasound in environmental medicine is being taken seriously for some time now. (6)
All previously valid protection standards, such as the Technische Anleitung (TA) noise and the DIN 45680, are based on the assumption that only sound which can be perceived by the ear can damage. (7) Other forms of the perception of sound are excluded. The measurement regulations are also not helpful, since only sound above 8 Hz is measured, although modern instruments can also detect frequencies of < 1 Hz and the infrasound range in the range 1 - 8 Hz causes particularly severe health impairments.
The prescribed sound measurements also average individual frequency peaks. They are based on the decibel A filter, which follows the human auditory curve in the audible sound range and averages on many different frequencies, instead of taking linear and narrow-band measures, as would be appropriate to avoid health hazards in the infrasound range. Furthermore, often obsolete measuring systems and microphones that do not measure accurately enough in the infrasonic range are still permitted within the scope of the currently valid regulations for measurement. As a result, the measurement of the sound phenomena that are harmful to human beings does not take place below 20 Hz.
Since these measurement regulations are the basis for approval procedures for technical systems, they must be adapted to the current state of the art. There would be a direct effect if the standards and regulations for the approval procedures of technical installations were at the level of the international state of knowledge. Were the standards for sound pressure to correspond to the state of the art, the limits for infrasound pressure would be set lower, the models for the propagation of infrasound would correspond to the state of research and the construction of wind turbines would be optimized in terms of emissions of low-frequency sound.
If technical sources of infrasound radiation are not removed quickly and sustainably enough by wind turbines, public complaints will develop into a health boomerang of the energy transition. A new national disease with cases like diabetes and cancer is to be expected. It is high time for politically responsible people to meet their protection obligation for humans and nature and to initiate the most important measures from the point of view of preventive medicine: an immediate moratorium on wind power development, greater minimum distances between humans and wind turbines, prioritise objective infrasound research coupled with modern measurement regulations in the corresponding DIN standards and stricter protective regulations directed at sound physics and biology.
(1) Lars Ceranna, Gernot Hartmann & Manfred Henger; “The inaudible sound of wind turbines - infrasound measurements on a wind turbine north of Hanover”, Federal Institute for Geosciences and Natural Resources (BGR), Unit B3.11, Seismology, 2004.
(2) A. N. Salt, J.T. Lichtenhan; "Perception-based protection from low- frequency sound may not be enough"; InterNoise 2012. http://oto2.wustl.edu/cochlea. A. N. Salt, J.T. Lichtenhan; "How does wind turbine noise affect people?", 2014.
(3) Alves-Pereira M, Castelo Branco NA; Prog. Biophys. Mol. Biol. 2007 Jan-Apr 93(1-3): 256-79. Epub 2006 Aug 4.; "Vibroacoustic disease: biological effects of infrasound and low-frequency noise explained by mechanotransduction cellular signaling".
(4) Claire Paller (2014). "Exploring the Association between Proximity to Industrial Wind Turbines and Self-Reported Health Outcomes in Ontario, Canada"; UWSpace, http://hdl.handle.net/10012/8268.
(5) Steven Cooper; "The results of an acoustic testing program Cape Bridgewater Wind Farm"; 44.5100.R7:MSC; Prepared for: Energy Pacific (Vic) Pty Ltd, Level 11, 474 Flinders Street, Melbourne VIC 3000, Date: 26th Nov, 2014.
(6) Robert Koch Institute; "Infrasonic and low-frequency sound - a topic for environmental health protection in Germany?", Communication from the Commission "Methods and quality assurance in environmental medicine". Position paper of the doctors for emission control (www.aefis.de)
(7) Standards: DIN 45680, 45401, 45651; Technical guidance noise (TA noise). "Acoustics - Attenuation of sound in outdoor propagation - Part 2: General calculation method". DIN EN 61260: 2003-03; "Electroacoustics - Band filters for octaves and fractions of octaves"; DIN EN 61400-11; "Wind energy installations, Part 11: Sound-measurement methods, acoustics, electroacoustics"; "Standard frequencies for measurements" (retracted), "Octave filters for electroacoustic measurements" (withdrawn).