Mark,
Don't you think that the actual frequency is quite low. Sounds like a
low air pressure pulse. Your ear drum senses the pressure change but
it is below the normal audible range.
It must be sub-audio below 10HZ and therefore below normal audio
recording equipment capabilities. It could possibly be illustrated
using a diaphragm sensor with a sensitive pressure gauge.
Ted
--- In "Mark Fischer"
<> wrote:
>
>
> Dear Roger,
>
> --- In "Roger Norwood"
> > Are you UK based? If so what locations are you describing, I find
> Nope-- California. I live right across the (Sacramento) river from
> what has evolved into one of the largest wind farms in the world. I
> mean hundreds and hundreds of mills, a significant fraction of which
> are the 90 meter giants built by Vestas.
>
> Earlier I had commented on how you can hear this sound, but you will
> be challenged to be able to get a recording of it.
>
> On this last instance I happened across the same effect, with a much
> smaller windmill that apparently pushes this phenomenon into higher,
> more clearly audible frequencies. 'Pylon thump'. Yep, that is a
> descriptive name.
>
> Now, while it is a sound that does not come from birds or the wind
> whistling in the trees, I'll take it over living next to an
> international airport any day of the week. For one thing you actually
> have to *listen* to hear it. ;^)
>
> As luck would have it there is not a breath of wind out there today.
> When I get a chance....
>
> Cheers,
>
> Mark
> ~~~~
>
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