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Waubra FoundationFebruary 1, 2015AustraliaAustralia

Acoustic Engineering Investigation into Airborne and Ground-Borne Pressure Pulses from Pacific Hydro’s Wind Turbines at Cape Bridgewater

A Simplified Explanation of the Findings, Previous Research, and the Consequences

Cape Bridgewater wind turbines

Waubra Foundation - 1st February, 2015

1. Background

  • Turbines create “waste energy” in the form of airborne pressure waves (sound) and ground-borne pressure waves (vibration).
  • Noise is that part of the sound frequency spectrum which is audible, but “noise” is also defined by psychoacousticians as “unwanted sound”.
  • The strength (sometimes expressed as a loudness in the case of noise) of the sound is measured in decibels (“dB”).
  • The wavelength of individual sound waves is a measure of the distance between the peaks of the pressure waves. The speed of sound divided by the wavelength gives the frequency of the sound and is expressed in hertz (Hz).
  • Where the frequency of the sound waves is below 20 Hz, the distance between the waves is relatively long, and the general term for this portion of the frequency spectrum is known as infrasound. Infrasound is only audible at very high levels (dB). However it can be damaging to the human body at levels well below audibility.
  • Impulsive infrasound from a variety of industrial sources has long been known to have the potential to be harmful to humans, especially with chronic exposure. For example, human and animal studies have shown infrasound directly causes both physiological stress,i and collagen thickening in a variety of tissues including cardiac valves, arteries, and pericardium which themselves lead to a variety of cardiovascular diseases.ii
  • Infrasound persists for much greater distances than audible sound and, unlike audible sound, penetrates well insulated building structures (including double glazing) with ease; and often increases the impact by resonating within the house, like a drum.iii iv This occurs, regardless of the source of sound & vibration energy. Penetration of buildings and amplification via resonance can also occur from sound and vibration from natural sources such as earthquakes and thunder.
  • Standards for wind turbine noise pollution in Australia are set in audible decibels (“dBA”) outside houses.v Use of dBA excludes accurate measurement of frequencies below 200 Hz, including both infrasound (0 – 20 Hz) and low frequency noise (20 – 200 Hz). These Standards do not require infrasound (either within or outside homes) to be predicted in planning submissions nor to be measured in the required compliance testing to the planning permit noise conditions. Most jurisdictions do not require wind turbine generated low frequency noise to be predicted or measured either (unlike other sources of industrial noise). In fact most noise measuring instruments and microphones are unable to measure accurately in the infrasound range, especially below 8 Hz, and some Standards explicitly specify the use of equipment which cannot measure infrasound.
  • Wind turbines produce infrasound along with audible noise. The more powerful the wind turbine the greater the proportion of infrasound and low frequency noise emitted,vi which then increases significantly if the turbines are sited too close together, now common practice in Australia.vii Most newer wind turbines are now 3 MW or 3.5 MW, compared to 2MW at Cape Bridgewater.
  • By the use of different sound meters and microphones, and in narrow (frequency) bands it is quite possible to identify and measure infrasound specifically from wind turbines, in the field. This unique “wind turbine signature” has now been demonstrated by the acoustic consultants involved in the Health Canada Studyviii and by Professor Colin Hansen’s team at Waterloo,ix in addition to Mr Cooper’s measurements at a number of locations in Australia prior to, and including, the Cape Bridgewater Acoustic Investigation.
  • Increasing numbers of residents living within 10km of wind turbines have suffered, and are still suffering, severe adverse health impacts since the wind turbines started operating.x xi Many have left their homes repeatedly, and eventually permanently, to live in greatly diminished financial circumstances, as their homes are no longer habitable or saleable. Some residents become too unwell to work. Wind turbines are not the only source of impulsive infrasound and low frequency noise causing severe health damage. The same pattern of identical serious adverse health effects, sleep deprivation and home abandonments, sometimes out to similar distances are being reported by neighbours to other known sources of infrasound and low frequency noise, at open cut coal mining (eg Hunter Valley in New South Wales), underground mines with large extractor fans (eg Lithgow, in New South Wales), gas turbine power stations (eg Uranquinty, in New South Wales, Port Campbell in Victoria) and numerous other sources (eg Tara gas field in Queensland).xii
  • Wind power projects and other energy generating noise polluting industrial developments involve very large sums of money in construction, in revenues and in the case of industrial wind turbines - public subsidies. It is not uncommon to find companies with large investments and large cash flows going to great and improper lengths to maintain their cash flows.
  • The wind industry has never been asked to prove that their machines are safe, unlike other products on the market. When queries are raised about impacts on neighbours, the industry and its supporters trigger the “Four Ds” of denial, dissemble, delay and destroy the messenger, despite the wind industry being well aware of the seminal research by Dr Neil Kelley and NASA which established direct causation of symptoms from impulsive infrasound and low frequency noise from wind turbines and other sources in the 1980s, by both field and laboratory research.xiii

2. The Purpose of the Cape Bridgewater Acoustic Investigation

The purpose of the investigation was simply to find out what was causing the symptoms and sensations, resulting in sleep disturbance and health damage, reported to Pacific Hydro between 2009 and 2014 by the residents of three homes sited between 600 – 1600 metres from wind turbines sited at the Cape Bridgewater Wind Project in Victoria, Australia.xiv

3. What Are the Key Findings of the Cooper Acoustic Investigation?

The findings include:

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