components into the +1kHz/noise floor track.
The result is full-frequency natural sounds, set against a clean
noise floor throughout the frequency range, without any hint or
residue of low-freq man-made noises. Any sounds below 1kHz are there
because you can hear they should be, and are as complete as the
source recording allows. As I said, it is a painstaking process,
especially with soundscapes that may be tens of minutes long.
I have prepared a set of files to show how this works in practise.
I've put them on our website, as they seemed to be too big for the
group's files section - download them from http://
www.listeningearth.com.au/DINR/
The recording is of Grey Francolins in Gugarat, India, with a jet
aircraft going directly overhead. It is not the dirtiest recording,
but it illustrates what can be done to improve things. My processing
frequency for this recording was below 1200Hz.
Files include:
Message: 1.
Subject: The raw audio file (with 100Hz brickwall filter),
Message: 2.
Subject: A simple attempt at filtering, using a highpass at around 500Hz,
with two parametrics attenuating major jet noise bands at 250Hz & 350Hz.
Message: 3.
Subject: The audio processed using DINR as described.
I've also included sonograms of each file so you can see what is
happening. The interesting thing to note is a dove calling around
800Hz, well inside the noise band. You can see how effectively it has
been retained in the DINR processing, whilst being compromised by the
eq filtering. Lastly two screen shots of the DINR settings for steps
3 & 4.
I hope this makes sense and is useful.
Cheers,
Andrew
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Listening Earth
Nature Sound Recordings; CDs & digital downloads
web: www.listeningearth.com.au
blog: www.listeningearth.com.au/blog
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