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)