[ASTRO] Re: Voices

[Michael Kepler <kepler@Metro1.com>]

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On Fri, 24 Apr 1998, Bart T. Lammey wrote:

<snip!>
> 
> Seriously, does anybody know of any sound-editing software that knows how
> to strip out the vocal track?  I've been doing some remixing of my own and
> have had trouble instrumentalizing...ie the vocals share the same general
> tonal frequency as the guitar or whatnot.
> 
> Full-blown technical lectures on sound engineering are welcome.

No time for a full-blown lecture at the moment but...
Just accept that you will never be able to perfectly de-construct
a mix into component instruments or voices.  I can explain why
well enough, probably, but not before putting everyone on the list
to sleep and annoying those who already know.  

However, you can do an 'ok' job of deconstructing.  How 'ok' is
extreemly dependant upon the nature of the source recording.  And
how 'ok' is good enough for your purpouses is up to you.

There are boxes that are sold that claim to 'remove' vocals from
recordings for karaoke or 'record it yourself' purpouses.  Trust me,
these are fairly simple devices and the results are highly variable,
full of sonic side-effects, and generally not very impressive.

The predominant technique for vocal removal is differencing.
This is a simple matter of using a differential amplifier to
literally subtract one track from the other of a stereo recordings.
This only works well if: a) it is a stereo recording b) there is
good channel separation c) the vocals are perfectly balanced between
the two channels and d) most of the other instruments are _not_
perfectly balanced.  The other instrument you usually lose with the
vocals is bass.  The whole balance of instrument volumes and timbres
gets thrown all out of whack, with favor given to any sounds that
are more exclusive to one channel over the other.  This often results
in a faint and "echoey" sound to the lead guitar, because the direct
sound is usually well balanced, but the reverberations that give
the recording a sense of "space" are not at any given moment perfectly
balanced.

By the way, differencing is a great way to eliminate some kinds of
unwanted noise, as long as you can accept all of the side-effects.

Some people may read this and then tell you "that's the old-fashioned
way, I know of this really sophisticated new method that works
much better!"  Trust me, they're just polishing the same old turd.

There is no magic, but there may be something good enough to
suit your needs.  Since you probably have a computer, there's lots
of sound editing programs that could probably let you invert one
channel of a stereo file and then mix it with the other, which
produces the same net effect of a differential amp.  Try it and
see what you think.  I'm using an ancient copy of Turtle Beach
Software's 'Wave for Windows', which could be used to do this,
with a little bit of extra effort.

Wow, that was longer than I intended.  I wonder how long the
"full blown lecture" would have been.

Mookie



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