Well, I attribute it to a few things and will have to return Curt to
that prairie to convince him.
This is a prairie of Switch Grass with no reflective objects for more
than a mile in any direction. THe Switch Grass in itself is sound
absorbant. This is a good chunk of land with infrequent man made
noise for over 4 miles. What I need to show Curt again is that this is
how an absorbant quiet natural space sounds and that it in itself is
now a rare sound field.
This is early spring when the "little critters" that are high pitched
have not returned in mass yet with just a few Song Sparrows and
Chippers around and the Chippers are still quiet. When the song birds
fill in the space in about two weeks the high pitches will be there.
The linear array looks like this but this setup was at a frog pond
later that same morning.
http://home.comcast.net/array1.JPG
I am having a lot of trouble mixing the surround from this frog pond
array. I have reached the conclusion that you do not want loud
directional sound sources within a distance equal to a circle that
could be drawn around the array. The problem I am getting is with the
end mics. The distant mic can be louder than the proximate mic and
this can not be solved by the ear on these short and abrupt calls. I
will report back if I can find a mixing solution or if I conclude that
my cube mic is just the much better overall solution. I do feel the
array would have worked if we would have backed it off the pond by
about 60'.
Rich
-- In Dan Dugan <> wrote:
>
> Curt Olson, you wrote:
>
> >We positioned the array in a
> >large open field about 200 yards from a very active waterfowl pond,
> >with mics oriented toward the pond. Later, playing back the center
> >stereo pair, I noticed there was almost nothing there above 8khz,
> >unlike other recordings I made that same day with that same pair.
>
> To what are you attributing this phenomenon? An interference
> cancellation from the ground reflection? That could make a "hole" in
> the frequency response if all the sources were in the same horizontal
> plane, but I wouldn't expect a low-pass effect, and my gut feeling is
> that it wouldn't happen that high in the spectrum. Maybe an
> atmospheric lensing effect?
>
> Were the outrigger channels at the same height?
>
> Also, the waterfowl I'm thinking of don't have much high frequency
> stuff, at least not compared with forest and bush critters. You would
> hear hf in the spashing, tho.
>
> -Dan Dugan
>
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