| Some proponents of the wind turbine industry have a tendency to communicate misrepresentations. I consider the following to contain examples .. INFRASOUND FROM WIND TURBINES - FACT, FICTION OR DECEPTION by Geoff Leventhall, Noise and Vibration Consultant, 150 Craddocks Avenue, Ashtead, Surrey (2006). It can be downloaded here. Following are excerpts from the document, counterpointed by my opinion of how I believe important issues have been misrepresented. | |
| Page 2: "There is no reliable evidence that infrasound at levels below its hearing threshold has an adverse effect on the body (Berglund and Lindvall 1995)." | At the time, Berglund and Lindvall (1995) was an eleven year old reference. Edition: 3 - 2006 of Definitions, Conversions, and Calculations for Occupational Safety and Health Professionals was a then current source indicating widespread acceptance of the contrary. |
| Page 4: "Modern up-wind turbines produce pulses which also analyse as infrasound, but at low levels, typically 50 to 70dB, well below the hearing threshold. Infrasound can be neglected in the assessment of the noise of modern wind turbines." | This is an astounding statement .. to call 70dB of infrasound a 'low level' simply because it is below the hearing threshold. The assumption continues that because this level of infrasound is inaudible, it can therefor be neglected. |
| Page 5: "On the occasions, such as unusually turbulent inflow conditions, when low frequency noise is produced by wind turbines, it may not be perceived as a noise, but rather as an unidentified adverse component in the environment, which disappears if the turbines stop, or if the inflow conditions change. This is because we are not accustomed to listening to low levels of broad band low frequency noise and, initially, do not always recognise it as a “noise”, but more as a “disturbance” in the environment." | The author appears ready to disregard a recognized effect, simply because it seems to be a "disturbance in the environment" rather than a "conventional noise". |
| Page 6: "It has been shown above that there is insignificant infrasound from wind turbines and that there is normally little low frequency noise. Turbulent air inflow conditions cause enhanced levels of low frequency noise, which may be disturbing, but the overriding noise from wind turbines is the fluctuating audible swish, mistakenly referred to as “infrasound” or “low frequency noise”." | On one hand, the author admits to 60 - 70 dB levels of infrasound. Then, he proceeds to dismiss them as insignificant. After conceding that there are enhanced levels of low frequency noise, and admitting to turbines' audible 'swish' being an overriding noise, he then portrays this noise as being objectors' concern with "infrasound". This tactic strikes me as a classic 3-step .. an unsubstantiated claim, followed by a right-angle misdirection, finished-up with a misrepresentation. |
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Page 6: "CONCLUSIONS: • Infrasound from wind turbines is below the audible threshold and of no consequence. • Low frequency noise is normally not a problem, except under conditions of unusually turbulent inflow air. • The problem noise from wind turbines is the fluctuating swish. This may be mistakenly referred to as infrasound by those with a limited knowledge of acoustics .." |
• The author leads with an industry standard, "If you can't hear it, it can't hurt you!" • Attention is kept to the immediate proximity of the turbine itself and intentionally limited to a possibility of turbulent inflow air. This keeps critical attention from what frequencies are being produced by air pressure variants (turbulence) downwind of the turbine. • I view this as a misrepresentation of peoples' understanding of infrasound and as condescending criticism of their intelligence. |
misreps.htm (June 27, 2009)