> And I would like to know what kind of background noise i am facing
> in this recording.
> https://dl.dropboxusercontent.com/u/43314821/example.wav
Philipp,
Straight off, the birds sound distant. I say this not just because of the
low level of the individual calls, but reverberation and echoes diffuse the=
calls, producing a chorus effect.
There is a lot of natural bass noise which muddies the birds. I use a
progressive gentle roll-off high pass filter (HPF) or "bass cut" on most of=
my high frequency sounds. I constructed this on the Audacity editor and I'm=
attaching the profile.
HPF800-2-4-6.gif
The reason for the smooth roll-off is to avoid resonances at the "turnover"=
frequency,
I'm also attaching spectrums from 8.000 to 10.000 sec.
Spectrum8to10.gif
Spectrum8to10HPF.gif
There is a mass of bass from the background sound below the birdsong
frequencies which doesn't contribute. This roll-off brings back the emphasi=
s
to the birds.
At the top end there is a sharp LPF cutoff filter with a steepness just
short of 60 dB per octave, starting at 7700Hz. This is audible for people
who don't go to discos, but especially listening slowed down, the bird
sounds are being muffled.
There is a stereo spread which makes to possible to place individual birds=
at least on headphones.
It is impossible to do a noise reduction as there is no point which is just=
noise. The check here is the "pile of bedclothes" test where the HF noise
level of your whole system can be heard and measured. However the HF hubbub=
on this recording is probably mostly distant birds and natural sounds, but=
if the HF response was there, I would expect to hear separate mic hiss at
the top end.
As general advice, I would try to get much closer to individual birds to
make them clearer against the general hubbub.
David Brinicombe
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