Trist, Sonia. Pacific Hydro Meeting with Cape Bridgewater Residents, June 2, 2014
From: Sonia Trist
Date: June 3, 2014
Subject: Pacific Hydro Meeting at Cape Bridgewater, June 2, 2014
Last night a meeting was held in Cape Bridgewater where Steven Cooper presented some preliminary results of his survey.
Our house featured in some of his graphs.
This material was available to the participating residents and PH before the meeting. We gave permission for the material to be presented at the meeting.
Our house is 600m from a turbine and is influenced by another 4 turbines within 1500 metres.
The graphs show a number of acoustic measurements recorded external to the house and in a bedroom.
All of the material relates to 10 minute samples using Steve’s multichannel recording system.
The narrow band spectrum information labelled 0 – 25 Hz covers the infrasound region.
The shutdown graph is for a westerly wind at 10 m/s as is the 100% power.
Comparing the two graphs show the presence of what Steve has called the Wind turbine Signature inside our house but not outside with the turbines operating.
With no turbines there are no such discrete frequencies.
I understand that those infrasound level are inaudible but are they are present.
The graphs show the infrasound without the turbines operating are what I am told is broad band noise.
The graphs for the frequency range of 0 – 200 Hz (that covers the low frequency sound) show the wind only to be broadband noise except for one peak that appears to be associated with frequencies measured in a turbine tower.
It seems that for some residents the low power settings cause a noticeable impact. I understand that the wind strength is much lower and just above the cut in speed for the tests. The infrasound peaks are there but at a lower level.
Apparently these results are similar to results recorded by Adelaide University at Waterloo in South Australia.
There are other graphs from Steve’s preliminary results that show variations in the A-weighted level that show different impacts of the wind speed and strength that are obvious when presented in a format of noise over the day, that simply do not show up in what he has described as the standard regression analysis method.