Hello
I'm an amateur too and I'm using Audacity to edit my recordings of
birds. And yes. The noise reduction tool is very useful, but it's
necssary to use it very carefully.
When I was listening Your de-noised half of recording I heard some
"digital" artifacts (in the bacground of the bird's voice) added by
Audacity's noise reduction algorithms. Maybe try to use the latest
version of Audacity (1.3.9 beta or "older" 1.3.6 beta) - in my opinion,
in this versions, there is better noise reduction tool than in the last
stable 1.2.6 version. Of course, maybe You already know it, but I don't
know, which version of Audacity You use.
Or maybe try to make two, "weakest" noise reduction, instead of "strong"
one. Experimenting is essential! ;)
Best regards
Krystian
Dnia 12-09-2009 o godz. 19:02 dannymeltzer napisa=B3(a):
>
>
> Yes this is basically what most commercial noise-reduction software does=
[in a very general sense]. It analyzes a sample of the 'noise' then
applies a 'fix' [based on that] to whatever longer segment of the
recording you are trying to fix.
>
> --- In "jmccubbinmd"
<> wrote:
> >
> > I'm relatively new to recording outdoor ambient sounds, but am very
intrigued by it. I have done plenty of audio recording (amateur), but
also have a background in astroimaging. I have been trying to solve the
noise floor problem with microphones, as it seems to bug everyone to
some degree. It just seems difficult and expensive to get rid of it.
So that got me thinking.
> >
> > For you audio engineers out there, please tell me if this is solid
thinking.
> >
> > When I take an astrophotograph, our exposure times are very long. The=
chip suffers from electronic noise, not unlike mic noise. To get rid of
it, we "calibrate" our images. One of the things we do is to take a
"dark frame" of equal length, at the same temperature, and same degree
of thermoelectric cooling of the chip. Then we mathematically subtract
the noise from the image and the image improves dramatically.
> >
> > As I was cycling through the countryside today it struck me that might=
be possible with microphone noise. So I tried it. I did some more
recording of my test subject (for now), the pond at our farm. I got a
clip of a bird chirping (my wife thinks it's a warbler, I'm not an
expert on bird calls, so and ID would be appreciated).
> >
> > I then recorded a 10 second clip with the microphones at the same gain=
in as quiet conditions as I could find in my study (full of books and
very quiet). I used that as my "noise floor sample".
> >
> > Then I imported the audio into Audacity (for simplicity) and first
amplified the bird call sample a fixed amount (19db in this case). I
then amplified the noise floor sample by the same amount. I then did a
high pass filter to get rid of a distant train passing (troublesome
buggers).
> >
> > Then I copied the clip with and without the noise reduction. In
audacity, you first take a "noise sample reference", then apply that
reference to the redording. Obviously, I used the noise sample and
applied it to the recording of the bird. The first half of his mp3 is
without noise reduction, just the 19db amplification and hipass filter. =
The second half is with noise reduction.
> >
> > I think it worked.
> >
> > If there is a better way of doing this, let me know.
> >
> > The equipment used here is a "matched" pair of Rode NT1-A's with foam=
wind guards, into a Sound Devices 702. The gain was set at 61.8db both
for the recording and for the noise sample as I felt this needed to be
exactly the same for both.
> >
> > Here is the comparison sample:
> >
> > http://m57.net/downloads/sfp/warblertest.mp3
> >
>
>
>
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