Information on wind turbine noise usually takes one of two forms; websites funded by energy companies or the green lobby would have you believe that they are whisper quiet. Meanwhile, anti-wind farm websites may seem to exaggerate the problems. We have to say that before we started researching this area, we had assumed that perhaps the noise issue might not be too serious. However, we have been quite shocked by the sheer amount of evidence building up on the internet that turbine noise can cause really severe distress to those living in the area.
Some of the issues involved in measuring noise are quite technical and difficult to understand. We’ve tried to explain them as simply as possible, but there is still quite a lot of information on this page. Let’s start with some quick questions and answers:

Q:    Do wind turbines produce noise?
A:    Yes.

Q:    Will this noise disturb me? Will it keep me awake?
A:     Nottingham University say no. We think that it is very likely that some local residents will be disturbed both day and night.

Q:    Are there any other health problems associated with wind farms?
A:    Some research has suggested that noise can cause a range of health problems.

Q:    Are there rules governing noise?
A:    Yes, but many people have argued that these do not provide local residents with protection from noise problems.

Some people near wind turbines report feeling the vibrations in their body, rather than hearing them, which keeps them awake at night. Meanwhile there is scientific evidence to suggest that certain parts of the human body may be sensitive to these very low level vibrations. This may explain why some people living near turbines seem to experience a range of health issues, often quite non-specific, such as feelings of anxiety, or generally feeling unwell. The fact that these symptoms are quite general, and therefore difficult to link conclusively to wind turbines, means that the wind turbine industry continues to deny that infrasound can affect people.

Noise is measured in decibels (dB), and environmental noise uses a special measurement called dBA.

• A very quiet room might be 30 dBA
• The noise from vacuum cleaner might be 75 dBA

This system can be quite confusing at first. It’s important to remember that for every increase of 10db, the volume doubles. For example, 20db is twice as loud as 10db. 40db is eight times as loud as 10db.
Before the turbines are built, noise measurements should be taken from a variety of locations on and near the site. For example, measurements may be taken from the gardens of nearby properties. These are to work out the level of “background noise”. These measurements should be taken at a range of different wind speeds, since this can affect how much background noise there is. This level of background noise is expressed in dBA, e.g. 40dBA.

These are set out in a document called ETSU-R-97. This specifies that in general the noise generated by a wind turbine should be no louder than 5db above background noise. So for example, if the background noise is 40db, residents may hear 45db of noise including the turbines. Remember that an increase of 10db sounds like a doubling of the volume. However, in quiet areas, different rules apply. ETSU-R-97 recommends a daytime limit of between 35-40 dBA. At night however, the limit is 43dBA. Incredibly, this means that turbines are allowed to create more noise at night than during the day.

There have been a large number of objections to ETSU-R-97. For example:

• The rules were published in 1996… but in those days turbines were much, much smaller than today.

• The rules assume that problems with noise are only caused by how loud it is… but there is no consideration given to other factors, such as the type of noise and the duration of the noise. However, we all know that some types of noise are much more irritating than others.

• The rules state that it is only necessary to measure wind speeds up to 12 metres per second… but they ignore the fact that faster wind speeds may cause turbines to generate more noise.
• The rules state that wind speed should be measured at a height of 10 metres… but modern wind turbines can be 125 metres high.

• The rules are about audible sound… but completely ignore the problem of infrasound.

• The methods used to calculate noise levels from wind turbines are not appropriate. The rules specify a special measurement called “LA90,10min” Here’s how it works: The noise levels are measured over a 10 minute period. The noisiest 90% of this time is ignored completely, leaving only the quietest 10% of the data. The noise level is then calculated as being the loudest noise in this quiet period. “the wind turbines could be making a noise like a jet plane taking off in next door's garden for nine out of every ten minutes. LA90, 10min would ignore that and characterise the noise based on the remaining one quiet minute.”
  
• The rules recommend that noise limits are set in relation to the nearest properties… but some types of noise are actually difficult to measure close to wind farms, and more noticeable a little further away, at distances of over 500 metres.
  

• The rules assume that background noise will help mask the noise of turbines. However, the type of noise produced by turbines is of a completely different type to normal background noise, so may not be masked.

The University of Nottingham say “no”. We would encourage you to have a good search around the internet, read both sides of the story, and make up your own mind. Here are some of the articles and downloads that we found useful while we were researching this page: