Meena:
The sounds of the ice are interesting and very musical; I wish I could have=
heard it there at that spot. Unfortunately, the recording has been swamped=
by severe wind overload that will be difficult to get rid of by any means.=
It seems at times that the wind has also overloaded the preamps of your re=
corder and these kinds of nonlinearities are also very difficult to eradica=
te. What kind of recorder did you use? It almost seems as though there was =
some kind of compression happening there.
Most all noise reduction methods, especially the ones in Cool Edit, use som=
e kind of FFT filtering which introduces pitched artifacts that were not in=
the original recording. Even small amounts of this type of noise reduction=
can turn a reasonable recording into something unpleasant to listen to, un=
less your intention is one as a composer using these artifacts in a musical=
way. I have given up on noise reduction for nature recordings (and most ot=
her recordings as well) and have used high-pass, low-pass and parametric fi=
lters in a judicious manner, instead.
So in the case of wind rumble, I would use one of the "scientific" high-pas=
s filters in Cool Edit and play around with the cutoff frequency and the fi=
lter order. That may be the best you can do in this case. You might also tr=
y some parametric EQ to bring out the sound elements that you want to hear =
and cut out some of the other noise. Is a simple high-pass filter the one y=
ou used in the recording labeled "quick filter"?
The best thing that you can for the future do is to get a proper Rycote bli=
mp for your shotgun mic, furry cover & all! Shotgun mics are notorious for =
being affected by the slightest amount of wind due to the long interference=
tube. It is most important to stop the wind from upsetting the microphone =
in the first place, then the rest is much easier. But for a shotgun in high=
wind, a good blimp is not even a magic bullet.
I would also suggest using a boundary microphone such as a good PZM with a =
proper windscreen that can be laid on the ground in high wind conditions. A=
n omni mic such as an AT-4022 would also be much better than a shotgun in h=
igh wind, but it still needs a good ball gag (spherical) windscreen with a =
furry cover to be effective. That particular mic also requires phantom powe=
r.
One last item: I am curious as to what is happening in the right channel of=
the original, unfiltered recording. I did not notice this in the others; t=
hey were all mono, left channel only. Is the right channel a processed vers=
ion of the original?
Take care.
-Greg
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