> The untouched recording for comparison is at:
http://soundcloud.com/petershute/111229-03brandyck
Peter,
The original recording doesn't seem to be set for
downloading so I had to record it. It's been through two
more MP3 stages. I've selected a section 8 minutes in as the
helicopter starts to circle - you can hear the main rotor
and the tail rotor and the birds react to the noise.
I haven't noise reduced the mid frequency mush as it could
be environmental noise and is less objectionable than the
hiss or deep rumble, which I bass cut. Both are very liekely
to produce artifacts from NR. I got away with 9dB NR, but I
usually use 6.
If you want the bass back in, the trick is to lay the
original track in parallel and mix in using the Envelope
Tool.
If you cross-cut as below, you can compare the hiss removal
and bass cut with the original. I've listened carefully to
the whole track and the reverb does not seem to be impaired.
Method
Re-recorded from Soundcloud
Equalization HPF800-2-4-6 bass roll-off
<curve name=3D"HPF800-2-4-6">
<point f=3D"20.000000000000" d=3D"-26.000000000000"/>
<point f=3D"200.000000000000" d=3D"-6.000000000000"/>
<point f=3D"400.000000000000" d=3D"-2.000000000000"/>
<point f=3D"800.000000000000" d=3D"0.000000000000"/>
<point f=3D"22049.000000000000" d=3D"0.000000000000"/>
</curve>
select sample 01:53 (from original start) for 1 sec
eq on sample HPF4000-3-6-9
<curve name=3D"HPF4000-3-6-9">
<point f=3D"135.000000000000" d=3D"-35.000000000000"/>
<point f=3D"250.000000000000" d=3D"-27.000000000000"/>
<point f=3D"500.000000000000" d=3D"-18.000000000000"/>
<point f=3D"1000.000000000000" d=3D"-9.000000000000"/>
<point f=3D"2000.000000000000" d=3D"-3.000000000000"/>
<point f=3D"4000.000000000001" d=3D"0.000000000000"/>
<point f=3D"22049.000000000011" d=3D"0.000000000000"/>
</curve>
Noise Removal - Get Noise Profile
cancel eq on sample (CTRL-Z)
Noise Removal: 9dB; 500Hz; 1.00sec
Saved original from 08:00 as
http://www.stowford.org/sounds/dr001508crop8=3D00.mp3
Saved noise reduced from 08:00 as
http://www.stowford.org/sounds/dr001508hpfnr9crop08=3D00.mp3
Load these as parallel tracks in Audacity
Mute one track and then flip using solo to compare
Have fun. :-)
David
David Brinicombe
North Devon, UK
Cogito cogito ergo cogito sum - Ambrose Bierce
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