Observations placeholder

Hear Res. 2010 Sep 1; 268(1-2): 12–21.
Published online 2010 Jun 16. doi:  10.1016/j.heares.2010.06.007
PMCID: PMC2923251
NIHMSID: NIHMS214369
PMID: 20561575
Responses of the ear to low frequency sounds, infrasound and wind turbines
Alec N. Salt and Timothy E. Hullar

The increasing use of wind turbines as a “green” form of energy generation is an impressive technological achievement. Over time, there have been rapid increases in the size of the towers, blades, and generator capacity of wind turbines, as well as a dramatic increase in their numbers.

Associated with the deployment of wind turbines, however, has been a rather unexpected development. Some people are very upset by the noise that some wind turbines produce.

Wind turbine noise becomes annoying at substantially lower levels than other forms of transportation noise, with the exception of railroad shunting yards (Pederson and Persson Wayne, 2004; Pederson and Persson Wayne, 2007; Pedersen et al, 2009).

Some people with wind turbines located close to their homes have reported a variety of clinical symptoms that in rare cases are severe enough to force them to move away.

These symptoms include sleep disturbance, headaches, difficulty concentrating, irritability and fatigue, but also include a number of otologic symptoms including dizziness or vertigo, tinnitus and the sensation of aural pain or pressure (Harry, 2007; Pierpont, 2009).

The symptom group has been colloquially termed “wind turbine syndrome” and speculated to result from the low-frequency sounds that wind turbines generate (Pierpont, 2009). Similar symptoms resulting from low frequency sound emissions from non-wind turbine sources have also been reported (Feldmann and Pitten, 2004).

On the other hand, engineers associated with the wind industry maintain that infrasound from wind turbines is of no consequence if it is below the audible threshold. The British Wind Energy Association (2010), states that sounds from wind turbines are in the 30–50 dBA range, a level they correctly describe as difficult to discern above the rustling of trees [i.e. leaves].

This begs the question of why there is such an enormous discrepancy between subjective reactions to wind turbines and the measured sound levels. Many people live without problems near noisy intersections, airports and factories where sound levels are higher.

The answer may lie in the high infrasound component of the sound generated by wind turbines.

A detailed review of the effects of low frequency noise on the body was provided by Leventhall (2009). Although it is widely believed that infrasound from wind turbines cannot affect the ear, this view fails to recognize the complex physiology that underlies the ear’s response to low frequency sounds.

This review considers the factors that influence how different components of the ear respond to low frequency stimulation and specifically whether different sensory cell types of the inner ear could be stimulated by infrasound at the levels typically experienced in the vicinity of wind turbines.