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Re: NR and echoes

Subject: Re: NR and echoes
From: madl74
Date: Sun Aug 18, 2013 2:21 pm ((PDT))
> If someone wants to have a go at it (increase gain, reduce noise, echoes =
intact), contact me off list and I can send the original wav file.

/H=C3=A5kan,

That's how your name shows on my system. :-(

I've done a noise reduction on your mp3 which is on:
http://www.stowford.org/sounds/130813_692_st12_storlom_editednr.mp3

If you send a FLAC version, I'll do it again.

Noise reduction using Audacity:

Select quietest sample 00:55 to 00:57, normalise, plot power spectrum.
 PS shows a general -6dB per octave slope with a slight tip-up
   above 15KHz possibly due to thermal noise - good
Restore level, apply custom HPF filter LPF800-2-4-6 (rounded roll-off)
"Noise Removal" -9dB; 500Hz; 1.00sec "Get Noise Profile"
Restore to non-filtered track
Select whole track, apply NR
Copy both tracks to edit window and flip using "mute" and clicking "Solo"
 result: HF noise is reduced, but not reverberation.

Some of my Audacity EQ curves are on
http://www.stowford.org/sounds/eqcurvesadd.txt

I'm on a laptop today and haven't been able to listen properly, but the
echoes seem the same with the hiss reduced. Can I have a go on a linear
track such as FLAC preferably without fades?

I hate most noise gates and expander "noise reduction" I also grind my teet=
h
when I hear an overloaded track with automatic record pumping and yell "Win=
d
the wick down!"

Audacity does expansion but this is unsuitable for quality recordings. This=

set of commands does a selected digital subtraction of the sample hiss and=

nothing else. The filtering avoids the other problem of generating audible=

artefacts at lower frequencies. The problem is the hiss, so I reduce the
lower frequencies in the sample and any artefacts get lost in the remaining=

noise. This preserves reverberation and echoes and sounds not in the sample=

which usually have less HF anyway.

David Brinicombe








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