Noise – it's enough to make you sick

EHN, the developers, intend to install up to 60 wind turbines, each producing 101 – 105 decibels. A jet flying over at 300 metres produces 103 dBA.

We understand that EHN have told Government officials that they predict the noise from the Molonglo wind-plant will be heard from 5 kilometres away. Publicly, EHN say that they don't need to consult with people who live 4 km away about noise issues.

EHN continue to tell residents living near the site that noise from sixty 101 and 105 decibel turbines will be within the limit of 35 dBA prescribed the noise regulations. Even 35 dBA represents roughly a quadrupling of our normal night-time rural background noise levels.

We believe that 60 turbines, each producing a noise equivalent to a jet flying over at 300 metres will be heard over huge distances and will exceed noise regulations for many residents. Disruption to sleep patterns, low frequency emmissions, loss of peace and quiet, and the related stress can cause health problems for people living near wind farms. Further information about these problems is detailed in the Proximity to residences section on this website.

The Danes are widely regarded as being world leaders in the wind-industry. To find out how noisy wind turbines can be, try use the wind-turbine noise modelling tool on the Danish Wind Industry Association website.

Will the wind "drown out" the noise of the turbines?

The wind-industry argues that the turbines only operate when it's windy and then the noise of the wind drowns out the turbines. People living near the proposed Molonglo Wind Farm noticed how still and quiet it was during most of the Autumn 2005 and Autumn-Winter 2006. Yet even while it was dead still and quiet night and day on the nearest property only 500m from the top of the Molonglo Ridge, EHN say they were still recording an average wind speed of 25 km per hour on the ridge-top. This is more than enough for the turbines to work. If there's wind on the top of the ridge, but no wind down at our properties, how will the wind noise drown out the turbines?

An explanation for this anomaly is given by physicist GP van den Berg, who found that wind turbine noise can be considerably higher than predicted, and that wind turbines can produce sound with an impulsive character. He says that methods used by wind turbine developers to predict noise are seriously flawed because they underestimate the wind-speed at hub height for tall towers. Van den Berg also says noise predictions do not reflect atmospheric conditions that affect the wind profile, especially at night. To read the full article, visit www.nowap.co.uk/docs/windnoise (PDF 624 kb - external link).

Construction noise

The soil composition of the ranges is largely rock and would almost certainly require blasting or pile driving for tower footings and materials and equipment pads. Construction noise will carry great distances.

Construction traffic (up to one additional traffic movement every 75 seconds) will be mostly heavy vehicles travelling through rural and urban residential areas, with resultant noise impacts, and dust from dirt roads.

Noise is not just unpleasant – it is a health risk

How does a wind farm rate against other common noises?

This decibel (dBA) table compares some common sounds and shows how they rank in potential harm to hearing. In many industries, workers are exposed to dangerous noise levels. This is particularly true in the construction, lumber, mining, steel and textile industries. Wind turbines are ranked in the top third, above the threshold where more than 15 minutes exposure a day is not recommended and way above the level where it is very annoying and intrusive.

• Printable version of this table (PDF – 61 Kb)

Related links

For more information about noise related to wind turbines, visit these websites. All these external links will open in new browser windows.

• Temperature Inversions and Sound Propagation (how the influence of a temperature inversion can sometimes cause distant sources of noise to sound much closer than they really are).

• Effects of the wind profile at night on wind turbine sound by GP van den Berg (624 kb).

• Specifications for Vestas wind turbines (showing 105 dB) (PDF – 148 Kb)

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