Hi-
Thanks for the helping me size-up the goals, everyone.
Without my prodding, a member of the Reserve Board took a firm stand
on potential negative sound impacts and opened the door. I think we
can request a full scientific study if done right. I'm leaning
towards a pilot study to demonstrate need. It could involve field
calibration and then recording a 345 kV or larger transmission system
at specified distances like .5 mile, 1500 ft; 900 ft; 600 ft, 300, ft
and directly under the wires. Also some long duration, preferably
simultaneous recordings maybe at 300 feet and 1500 ft. Best if done
a few times at the same spots during spring migration, peak song bird
nesting and fall migration. Are there other recordists who would be
interested in participating? Of course, living within driving
distance of 345 kV or larger transmission line passing through a
fairly natural area is a must too.
Greg, I could not access your High Voltage study attachment. Rob
At 2:10 AM +0000 3/18/11, Avocet wrote:
>
>
> > Using
>>
>><http://www.sengpielaudio.com/calculator-air.htm>http://www.sengpielaudio=
.com/calculator-air.htm
>>I get about 6dB loss
>> per 100 feet. So assuming an additional drop in the noise of -12 db
>> (-20 db total under background ambience) would still mask
>> communications, we get 150' + 200' or 350 feet on both sides of the
>> cables at 11 K hz.
>
>Rob,
>
>Yes, but they will shoot you down in flames of you don't include all
>the variables. In addition you have the DB drop due to distance, which
>is not quite inverse squared at 6dB per double the distance. At 30KHx
>sengpiel gives -28dB at 100 feet plus distance loss, so the high
>frequency response of audio mics is academic.
>
>Electromagnetic radiation is more important. This comes from corona
>discharges especially in wet an icy weather. Electric companies will
>quote warm and dry figures. In effect, the whole line is a giant radio
>antenna which loses a percentage of the power it transmits (in
>gigawatts).
>
>What effect does the alternaiing magnetic field have on birds which
>use the Earth's magnetic field for navigation, like pigeons? I don't
>know and I don't think anyone knows as the research hasn't been done.
>
>> condenser capsules mostly can
>deliver dozens of khz. so you probably better use a microphone built
>for measurement purposes.
>
>Or a bat detector as in my earlier message. Here's one, the songmeter:
><http://www.batecho.eu/html/frame18.html:>http://www.batecho.eu/html/frame=
Message: 18.
Subject: html:
>
>> As for determining "public necessity" for the double circuit 345Kv
>> line, our studies suggest so far that the high capacity project is
>> not needed.
>
>The usual argument is that they are needed to "average out"
>intermittent wind power, which is my anti campaign. This is adding
>insult to injury after the turbines have chopped up large numbers of
>bats and birds. Wind power is a highly visible "greenwash" with very
>little overall benefit, but that's another campaign. I've always
>maintained that nuclear energy is the answer. Don't try that one now.
>:-) Of course the real solution is to stop extracting oil and gas but
>I'm not putting any money on that one either.
>
>David
>
>David Brinicombe
>North Devon, UK
>Cogito cogito ergo cogito sum - Ambrose Bierce
>
>
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