Hi--
The transmission companies in the US are allowed do their own studies
that say these utltra high voltage power lines are harmless and, in
fact, are a benefit to the environments they pass through. This needs
responses from many perspectives.
Yes, bird strikes are a huge negative impact. About 200 dead birds
per mile is typical. I've got material on that thanks to the State of
CA.
I've not come across any animal communication studies that address
transmission lines. Imagine it this way: 6- 1" diameter cables
sweeping through 30 miles, 110-180 feet above marshlands, wetlands,
grasslands, river bottoms, transition and mature wooded areas. Under
these wires is a 150' wide clear-cut path that is sprayed with
herbicide 2-3 times a year in wooded areas.
Under dry conditions which are _much quieter_ than in high humidity
and circa freezing conditions, the wires create, 24/7, a dense sheen
of harmonic frequencies starting at 7 K Hz extending to 80 KHz or
higher (I've read they use ultra-sonic detectors to confirm that its
working correctly). The spikes are -8dB from the loudest element in
the natural setting-- distant traffic. I'd have to check, but I'd
guess that distant bird communications are typically -12 to -18dB
under the ambient background sound level. If these numbers are even
close, transmission mission noise creates significant masking of
animal communication -- especially around 11K Hz. How far from the
lines would masking happen? Using
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. 700 feet =3D a 1/6 mile wide compromised
communication strip from horizon to horizon.
You tell me, would nesting couples that communicate in this range
keep moving? The location I'm addressing is rare habitat but the
whole area where the 210 mile long line would run is important
habitat.
As for determining "public necessity" for the double circuit 345Kv
line, our studies suggest so far that the high capacity project is
not needed. Electric use is down in Wisconsin-- as it is all over the
US except in states where air conditioning is a major use. More
here: http://tinyurl.com/622za3r
=3D=3D DO YOU SUPPORT THIS POSITION ???=3D=3D
If folks who have experience with spectrograms for birds can go
through the list and mark species they know have rich Hz content from
8-20K Hz on this spread sheet,
<http://tinyurl.com/4jjcgkz>http://tinyurl.com/4jjcgkz
that would really help the case I'd like to start developing. Add bat
and other species at the end and return it to me. Thanks!
If you want to sign a request that the company needs fund a third
study of potential animal communications and disturbing nesting
habits, send me an email < > The request has to go in by
3pm today.
Rob
=3D =3D =3D
At 12:21 PM +0000 3/16/11, neuroCO.UK wrote:
>Hi Tom, I particularly look forward to that recording
>Regards
>
>--------------------------------------------------
>From: "Tom Williams" <>
>Sent: Wednesday, March 16, 2011 12:16 PM
>To: <>
>Cc: "vickipowys" <>
>Subject: Re: [Nature Recordists] Transmission Line Noise & Animal Talk
>
>> Hi Vicki, Rob,
>>
>> Apologies, this clip wasn't originally recorded with analysis in mind
>> hence
>> the low sampling rate. I might be in that area again at the weekend, if=
so
>> I'll try and get another recording with my AT4022s at 96kHz.
>>
>> Cheers,
>>
>> Tom
>>
>> On 15 March 2011 20:25, vickipowys <> wrote:
>>
>>>
>>>
>>> Rob,
>>>
>>> I downloaded this WAV sound clip but it is only 44.1 / 24 bit. Needs
>>> a higher recording bit rate to show higher frequencies on a sonogram.
>>>
>>> cheers,
>>>
>>> Vicki
>>>
>>> On 16/03/2011, at 3:05 AM, Rob Danielson wrote in part:
> >>
>>>
>>> > Here is a soundfile clip http://tinyurl.com/4f6b3ar (orig, only
>>> > boosted +12dB)
>>> > & sonogram http://tinyurl.com/464ufe3
>>> >
>>> > Here's what I could use quick help with if people hav some time:
>>> > (1) a sonogram of the above sample that goes higher than 24K Hz
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
>> ------------------------------------
>>
>> "While a picture is worth a thousand words, a
>> sound is worth a thousand pictures." R. Murray Schafer via Bernie Kraus=
e.
>>
>> Yahoo! Groups Links
>>
>>
>>
>>
>>
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>>
>> The message was checked by ESET NOD32 Antivirus.
>>
>> http://www.eset.com
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>>
>
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>signature database 5957 (20110316) __________
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>The message was checked by ESET NOD32 Antivirus.
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>http://www.eset.com
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>
>------------------------------------
>
>"While a picture is worth a thousand words, a
>sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.
>
>Yahoo! Groups Links
>
>
>
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