....Or maybe a wind farm/ wind generator up on one of your ridges ?
Chris
http://www.wildechoes.org
--- In Dan Dugan wrote:
>
> > I made multiple recordings in various rooms of the house and the
> > cellar and porch today, and outside pointing the microphone in four =
> > directions. The noise is there in all recordings, loudest outside,
> > quietest in the cellar.
> >
> > The frequency is low, around 45 Hz with clear harmonics. The
> > intensity is low, around 5 dB SPL inside and about 15 dB SPL outside. =
> > Those numbers are very, very approximate. I do not have a SPL meter =
> > that reads that low, so I extrapolated based on the levels in the wav =
> > file. Also, in order to hear it at all and have the harmonics show up =
> > in a spectrum image, I had to apply a High Cut filter above 100Hz.
> > Otherwise it is buried in mic noise and whatever else.
> >
> >
>
> I would suspect that someone has a generator running. Low frequencies tra=
vel a long way.
>
> -Dan
>
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