cleaning audio files

[Nick Thieberger]

Thanks to all who responded about audio noise reduction. Below is a
summary of responses received both on- and off-list.

A number of responses referred to Audacity (Simone Graetzer, Colleen
Hattersley, Alex François), also SoundForge (Colleen Hattersley)
+++++++++++++++++++++++++++++

We've used Adobe Audition and Soundbooth, I think their filters for
broadband noise reduction are slightly better than the one in Audacity
but you also get the 'wobbly' noises and robotic sounding voices
depending on how many dB you're cutting the noise with. Quite possibly
you would obtain better results with dedicated audio restoration tools
such as the ones you mention or the WAVES plugins or CEDAR tools, I've
heard the CEDAR stuff on a trade show several years ago and it sounded
quite impressive but it also had an impressive price tag, not really
justifiable for us for the odd noise removal job. The WAVES plugins as
well as the SoundSoap tools are available as demo versions so you
could try them before deciding on buying them. I would always only
apply any such filtering on a copy for transcription purposes and keep
the original as well for archiving.

Paul Trilsbeek
+++++++++++++++++++++++++++++
 Sound Soap is great for removing the noise from recordings of LPs but
it may not be very flexible. The old Cool Edit Pro (before it was
changed to Audition by Adobe) had a great noise reduction algorithm. I
think Adobe Audition still has retained the feature but the whole
package is a little overpriced. If you are just trying to get rid of
electrical hum you can use EQ to remove the fundamental + harmonics
but for white noise you will need something that is adaptive (Sound
Soap Pro does have these features).

Hywel Stoakes
+++++++++++++++++++++++++++++
there was a cheap version of SoundSoap that could be used as a plugin
to the Bias Peak software. Handy if you have Peak. The interface is a
little obtuse, but does a good job.

Audacity has a noise removal effect..but I found the results were not
as good as the soap.

If you have Soundtrack Pro, again, there's a Noise Reduction process.
http://www.macprovideo.com/hub/soundtrack-pro/howto-removing-background-noise-soundtrack-pro

..and Waves make an alternative to Soundsoap:
http://www.waves.com/Content.aspx?id=205

Ben Foley
++++++++++++++++++++++++
I have used SoundSoap quite extensively.  Especially with tape
cassette or reel-to-reel analog recordings.  However, occasionally, I
have used it for uneven digital audio that has distortion in it or
audio with ordinary background noise (like in a restaurant setting).
It is affordable and easy to use. The audio sample is played back
within SoundSoap and the noise is automatically detected and you can
visually see what artifacts are present and make adjustments both
visually and by ear.  After some practice you can see how some
adjustments might even take away portions of your audio that you might
deem significant.

However, the only draw back is that its noise removal is a singular
event across your whole recording.  So you may need to adjust
accordingly if you have segments of audio that have different types or
kinds of distortion in a single recording.  What I have done, of
course, is use SoundSoap in conjunction with additional audio editing
software to get the results I need.

One additional software I use is AudioRefurbish, a mac only
application as far as I know.  With AR I am able to adjust the various
levels of the recording  especially where the voice is concerned.
Such improvements have actually produced clearer audio segments of
voice that were never realized before, say for example in a wax
cylinder recording that had soo much distortion that you could not
hear anything.  After several runs thru SoundSoap, adjustments in
AudioRefurbish really brings out the sound qualities of an overall
recording.

Phil Cash Cash