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RE: noise reduction-parametric eq-a basic example

Subject: RE: noise reduction-parametric eq-a basic example
From: "Martyn Stewart" <>
Date: Mon, 29 Nov 2004 16:56:57 -0800
Nice simple example John....

Martyn

Martyn Stewart
Bird and Animal Sounds Digitally Recorded at:
http://www.naturesound.org
N47.65543   W121.98428
Redmond. Washington. USA
Make every Garden a wildlife Habitat!

425-898-0462


-----Original Message-----
From: John Hartog  
Sent: Monday, November 29, 2004 1:39 PM
To: 
Subject: [Nature Recordists] noise reduction-parametric eq-a basic example



The program I have been using, Cubasis VST, doesn't have any 
fancy noise filters, but it does have a parametric equalizer.   I 
have found this equalizer to be pretty good at reducing unwanted 
noise.  In case someone out there doesn't know to use a 
parametric equalizer, here is a basic example of how I use it. 

The other day I went out to a local, urban wildlife area to test how 
well two Shure183s sound as steroe in a parabolic dish - I 
recorded some chickadees and some other small birds, maybe 
bushtits, in a small oak tree. 
<http://groups.yahoo.com/group/naturerecordists/files/041121a.
mp3>

As you can hear, there is a lot noise from the surrounding roads 
-  low rumbling and howling.
The parametric equalizer I use has two sets of three adjusting 
knobs:  Gain, Frequency, and Q.  
With the gain knob you can cut or boost; with the frequency knob 
you can center on a particular frequency; and with the Q knob you 
can adjust the bandwidth affected.

The first step is isolating the frequency of the noise. To do this, I 
set the Q for the narrowest bandwidth, boosted the gain up, and 
swept through the frequencies until the noise comes through 
loudest.  In the recording, the rumble is loudest at about 72Hz.  
Next cut the gain and abracadabra the rumble disappears.  
<http://groups.yahoo.com/group/naturerecordists/files/041121b.
mp3>

Now the rumble is better but the howling is still there.   The 
equalizer in the program I am using allows two sets of 
adjustments for each pass.  So, on the second set of knobs I go 
through the steps again:  boost the gain, isolate the frequency, 
cut the gain.  The howling seemed to be centered at  around 
254Hz.  
<http://groups.yahoo.com/group/naturerecordists/files/041121c.
mp3>

Well, is that any better?  Do the birds still sound good?
This just a rough example, thrown together pretty quickly.  It 
usually takes more messing around to get it right, and if I tried it 
again I'm sure I would do it a bit differently.
-John Hartog







"Microphones are not ears,
Loudspeakers are not birds,
A listening room is not nature."
Klas Strandberg 
Yahoo! Groups Links



 






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