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Re: Odd acoustic effect

Subject: Re: Odd acoustic effect
From: "freitojos" freitojos
Date: Thu Apr 12, 2012 12:53 pm ((PDT))
there are hollow gurgling sounds from the stream
> which are probably from the rocks or whatever the stream was
> running over. I've got a steep stream here which plays
> tunes.

David,
I am sory for my confusion there is no ressonance is the strong water in th=
e rocks, and the wall was irregular and a grass wall in fact, in those deep=
 valeys is impossible to escape walls at 45=BA to 90=BA. And of corse you a=
re right the HPF makes the water thin and is good for birds only.Here is an=
other recording now in a much stronger river the same setup in a 45=BA desc=
ent pointing at 90=BA from the river  with tal grass 50mts from the river i=
n a very deep valey:
http://soundcloud.com/freitojos/20120401t0700z-the-bestan-a-in
Here the water masks the birds.
I think these places are very dificult with the microphone positioning, as =
you have said David I must try and listen the various locations.
Thank you,
Jos=E9

--- In  "Avocet" <> wrote:
>
> Jos=E9,
>
> Nice recording. For starters, you've got two of the World's
> best mics there and they are working well together as an M-S
> pair. I can't hear a wall pickup and if it was there it
> would show up as an out-of-phase effect. Theoretically there
> should be a peak from the wall 100cms away at around 170Hz.
> (340 / 2.0m) There is a small peak at 200Hz but perhaps the
> stream is not producing much at those frequencies. There is
> a big dip in the spectrum at 20Hz which may be due to the
> landscape and may worry a passing elephant. :-)
>
> If you have a wall reflection at higher frequencies, it
> would show up on the fig-8 S mic which has an equal back
> response, but you may be losing that if the mics are low and
> in grass. Next time listen as you move the mics around to
> see what the wall is doing.
>
> The first thing I did with your track was to undo the
> bass cut with a 6dB/octave bass lift. The HPF was fine for
> the birds but not good for the stream, making it sound too
> thin. There isn't a sharp resonance like I got (and
> incidentally haven't heard since after dozens of plane
> passes) but there are hollow gurgling sounds from the stream
> which are probably from the rocks or whatever the stream was
> running over. I've got a steep stream here which plays
> tunes.
>
> My preferred mix (Using Audacity) is to copy the original
> track, use the 6db/octave HPF on one copy and a softer HPF
> on the other (mine was HPF800-1-2-3 which falls at 1dB for
> the first octave, 2dB for the next and 3dB per octave
> thereafter) I mixed in the second (low frequency) water
> track at about -12 to -6 db.
>
> David
>
> David Brinicombe
> North Devon, UK
> Cogito cogito ergo cogito sum - Ambrose Bierce
>








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