Cooperative Measurement Survey and Analysis of Low-Frequency and Infrasound at the Shirley Wind Farm
From comments by acoustician Rick James:
Three families in the footprint of the Shirley Wind project (owned by Duke Energy) have reported adverse health effects since the wind turbine utility commenced operation. Two have been forced out of their homes. They report experiencing symptoms of the type associated with wind turbine syndrome. These families offered to act as interveners in another Wisconsin case, Highland Wind, which is in the application hearing phase. Fifty affidavits were filed by them and other residents near the utility describing adverse health effects and home abandonment for the eight-turbine Shirley Wind project which uses Nordex N100 2.5 MW wind turbines. This study was requested by, and partly sponsored by, the Wisconsin PSC. The purpose was to determine whether infrasound was present in the homes of the three families.
The homes of three families were studied, two of whom (R1 and R3) are my clients for whom I have also conducted sound testing for infra and low-frequency sound and confirmed its presence. R1 is about 3500 feet [about 2/3 mile; ~1 km]; from the nearest wind turbine, R2 is about 1100 feet [about 1/5 mile; about 1/3 km], and R3 is about 7000 feet [about 1-1/3 mile; ~2.1 km].
Initially the PSC was going to have the study conducted by George and Dave Hessler. This posed a major problem for credibility with the interveners and others who know their position from other projects. The Wis. PSC staffers have a long relationship with them because they have done numerous studies for wind utilities in the state and have always given the utilities’ a clean bill of health claiming that sound levels at complainant’s homes met the state limits and that infrasound and low-frequency sound was not a problem. The attorneys for the citizen’s group, Anne Bensky and Peter McKeever for Forest Voice, and Glenn Reynolds, the attorney for the Town of Forest which also opposes the project, wanted the tests to be conducted but were concerned that the Hesslers would produce a biased study. It was decided that they would push for a study that included four acoustics experts, some on the wind industry side (Hesslers), independents (Schomer and Walker [Channel Islands]) and one who has demonstrated the ability to find infrasound inside homes (Rob Rand). I was not available on the proposed test dates so I could not participate but Rob Rand was a very good alternative. This also leaves me free to do my own evaluation of the study and collected data and audio files. I believe that the participation of the Hesslers and Clean Wisconsin make it much harder for the wind industry trade associations to claim that this work is biased.
All three homes were found to have measurable infra and low-frequency sound from the wind turbines with levels decreasing as distance increases. …
Although there are details in the report that I would take issue with, I can say that the team portion of the report presents a major step forward in the discussion about why adverse health effects are being reported by people living near modern industrial scale upwind wind turbines. The primary conclusion of the team is:
The four investigating firms are of the opinion that enough evidence and hypotheses have been given herein to classify LFN and infrasound as a serious issue, possibly affecting the future of the industry. It should be addressed beyond the present practice of showing that wind turbine levels are magnitudes below the threshold of hearing at low frequencies.
The argument about whether wind turbines produce infra and low-frequency sound and if they do, whether it is sufficient to cause adverse health effects has taken a big step forward with this conclusion. That infra and low-frequency sound is a primary characteristic of wind turbine acoustic emissions was established by the team. The argument that infrasound produced by modern upwind wind turbines does not have sufficient amplitude to reach the threshold of hearing (set for steady pure tones, not the complex mix of tones emitted by wind turbines) —raised by the wind industry through its experts like Dr. Leventhall and the many acousticians and others who parrot his opinion – is now discredited.
I think this is a major step forward. We still need to establish what levels and other characteristics of infra and low-frequency sound are needed to produce adverse health effects, but the argument that it is not present is shown to be false. The wind industry and its supporters can no longer say that wind turbines do not produce significant levels of infra and low-frequency sound just because the sound pressure levels do not rise to the thresholds of perception of audible sounds.
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