Justin,
If you're looking to clean up a recording with aircraft noise, you
may not have to butt-edit out the whole 7-8 minutes. Aircraft noise
in the far distance is very low frequency, and can be effectively
filtered. Its only when the plane is coming more overhead that it
gets louder and starts spreading noise up into higher frequencies.
So with judicious filtering only a few minutes may be irredeemable.
There is an art to this, and it depends upon one's intended outcome
as to how drastic or subtle the filtering can be. If you're preparing
a sonogram, one can get away with a lot more noticeable filtering
than preparing audio for enjoyable listening.
What I do is first run a high-pass filter. I'll usually choose one
that rolls off below about 100-150Hz. Then I use Digidesign's DINR
plug-in to suppress sounds up to around 300Hz that are LOUDER than
the ambient threshold. Essentially I'm blending sounds back to the
ambience level, not filtering them out and thus creating a frequency
vacuum. Sometimes a few subtle passes is required to create a
realistic effect. Most of a natural soundscape occurs above 300Hz,
but there will be a few things that come below, such as wingbeats,
mammal calls, birds with booming calls, coucals, pigeons, ratites
etc. So the final step is to go back and look for those low-frequency
components and restore them one by one from the original audio. This
involves finding a filter setting that allows the natural stuff past
while filtering the noise. A sonogram of the specific sound may help
identify how to isolate the frequencies you wish to keep.
Its an involved process to try and describe, especially that final
sculpting of sounds, which can be quite time consuming. DINR is an
essential plug in for this. None of the other NR plug-ins (Sound
Soap, X-noise..) have the necessary configurations.
These techniques are also applicable to cleaning up less intense wind-
buffeting.
Cheers,
Andrew
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