RECORDING November 2024 - 38

Studio
Audio Repair
101
I often have an issue with lip smacks in vocal recordings, which
are much more difficult to eliminate after the fact with traditional
editing. Today, de-click modules/plugins do a great job of removing
them without cutting into the voice, providing a much faster
and more transparent solution.
For outdoor or location recordings (like dialog captured live in
a film shoot or during electronic news gathering), today's " smart "
AI-based processors can even specifically target the kind of broadband
noise that results from wind hitting a microphone or the sound
of a lavalier (clip-on) mic rustling against the speaker's lapel.
A Word of Caution
While restoration processes have come very far in the past 20 years,
some caution is still needed when removing unwanted problematic
sounds embedded in a recording. The more you dig in and try (and
try) to remove the offending sound, the process may introduce artifacts
of its own, most often a swishy, aliased sheen, not dissimilar to lossy
codec compression. So, while repair software may not always be able
to achieve 100% effectiveness, the results keep improving with the ongoing
development of more sophisticated AI tools.
Bleed
Bleed (aka leakage) occurs when sound from other instruments
or the performer's headphones bleeds into the mic. Arguably,
bleed is the most problematic on vocals, as well as snare drum-
usually from the hi-hat.
In most cases, it is difficult, if not impossible, to effectively gate
or EQ out the bleed. A dedicated de-bleed or advanced drum
gate module looks to address this issue. It's a bit tweaky and requires
access to the sound that bled into the mic in the first place.
The user might even have to align the original audio of those
tracks with the bleed signal in the vocal/snare track to enable
phase cancellation to be employed to eliminate the leakage. Still,
despite the extra work involved, I have gotten it to work surprisingly
well on occasion.
Specialty Tools
Some audio repair modules address issues that are even more
difficult to deal with-problems that previously might have been unfixable.
In the old days, prominent distortion in a recording (like the
nasty digital clipping from an overloaded ADC) usually meant that
the recording was unusable. However, modern de-clipping repair
tools can analyze the clipped waveform and generate and restore
the parts of the wave (positive and negative peaks) that were cut off,
thus eliminating the distortion that resulted from the clipped peaks.
Bye-Bye Verb
Years ago, if a recording had too much reverb or ambience
picked up by the mic, there wasn't much that could be done to
reduce it. A little noise gating might
shorten the reverb tail, but often, this
created a noticeable, unnatural cutoff.
Today, modern de-reverb process
can address this issue, providing a
significantly drier vocal track. This is a
complex process, and while I've gotten
surprisingly effective results with
overly " wet " signals, this is one that, if
pushed too far, will result in the artifacts
described earlier.
38 RECORDING November 2024
Match Game
Some audio repair tools are more geared to providing useful
processing for mixing or mastering than actually repairing audio
or removing unwanted noise. A matching EQ analyzes the tonal
balance of two signals-one with a desirable tonal balance and
another that needs tonal correction. It then applies the tonal print
of one to the other. This can be useful in situations like a vocal
comp or guitar part, where the tone is noticeably different when
pieces of one take are combined or punched into another. While
it's possible to use an EQ and do this by ear, a matching EQ
plugin makes the process much quicker and accurate. Similar capabilities
can be found in ambience-matching modules.
Wow and Flutter
Old tape recordings (especially cassettes) can suffer from wow
and flutter, periodic pitch variations that give the music a seasick,
out-of-tune character. Dedicated wow and flutter processes can
now straighten out the pitch variations, restoring steady playback
that is perfect for digital transfers. Although not publicly available
as a plugin for " home use, " the most advanced is the Plangent
Process (plangentprocesses.com).
http://plangentprocesses.com
RECORDING November 2024

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