The beauty of digital audio is its promise
of pristine quality. No clicks, hiss or
scratches that were the norm of vinyl
and tape recordings. That's not to say
that all digital audio is noise-free.
Far from it. Poor recordings can still
be made in the digital medium and recordings
that have been transferred from analog
(vinyl records or cassettes) to digital
will retain some of their noise.
Fortunately, cleaning up digital audio
is a fairly easy process. There are many
software packages on the market specifically
designed for reducing specific types of
noise in digital recordings. Not all of
them are suitable for all types of noise,
so it's important to analyze the type
of noise you are trying to get rid of.
Most noise reducing software has a function
for removing background hiss. This works
by capturing a profile of the background
noise. The profile is used to create a
filter that matches the characteristics
of the noise. To use this function you
must select a quiet section of the audio
to get a sample of the noise you want
to reduce. A good place to take your sample
from is between songs or the first second
or two before the audio actually starts.
The sample does not have to be long -
half a second is all you need - but it
can't be music or voice - it should represent
a silent section.
This noise profile will help you to reduce
exactly the right kind of noise from your
audio recording. It is useful for reducing
background hiss, but clicks and pops need
another kind of processing.
Pops and clicks are of two flavours -
digital and analog. Digital clicks can
be caused by processor overload as you
make a digital recording. The recording
"stops" for a moment and the resulting
skip creates a very short click. Digital
clicks are easy to detect and most noise
reduction software does this automatically.
Analog clicks and pops are caused by
scratches and imperfections on vinyl and
their duration is much longer than digital
clicks. To remove this type of noise,
a special filter is needed to automatically
detect and remove the unwanted sound.
Settings can be adjusted to match the
size and frequency of the noise.
There are several audio packages on the
market that are specifically designed
to reduce noise from vinyl and cassette
recordings. They allow you to capture
the audio digitally by connecting a turntable
or cassette deck to the sound card on
your computer. Once the audio is stored
on the computer, it can be processed to
remove background hiss and clicks. Most
presets will give you adequate results
and you will be able to enjoy your old
recordings in the digital domain.
ABOUT THE AUTHOR
Ross is an enthusiast audio professional
take advantage of his knowledge about
MP3,
AAC,OGG, FLAC SHN and other compression
techniques
