The rapidly spinning blades of huge wind turbines have an effect on their surroundings, and it goes beyond aesthetics. The rapidly spinning blades can produce a weak but distinctive noise, as well as disruptions in air pressure. The noise is generated by the movement of the blades through the air, as well as from the from the turbine machinery.
Infrasound, is sound that is lower in frequency than 20 Hz or cycles per second. That's the "normal" limit of human hearing. infrasound is the primary issue for those concerned about wind-turbine syndrome. They also say that audible sound and vibrations coming from wind turbines contribute to the health problems reported by some people who live close to wind farms. Symptoms of wind-turbine syndrome might include:
- Sleep problems
- Night terrors
- Ringing in the ears (tinnitus)
- Mood problems (irritability, anxiety)
- Concentration and memory problems
- Issues with equilibrium, dizziness and nausea
These symptoms have been observed and documented by a limited number of scientists studying small groups of people, and the scientific community hasn't concluded whether wind-turbine syndrome exists. There are also mixed opinions on whether wind turbines emit infrasound and if the amount is any more than that emitted by diesel engines or waves crashing on the beach. But we do know that at high speeds, wind turbines can produce an audible hum and vibration that can be carried through the air.
It's these sounds and motions that provide clues and possible solutions to wind-turbine syndrome, which we'll explore in the next section.