Re: Voice processing technology

[gatech.edu!mit-eddie!gaffa.mit.edu!jsd@cs.utexas.edu (Jon Drukman)]

In article <3801@ur-cc.UUCP> boris@prodigal.psych.rochester.edu writes:
>Ever since I heard Laurie Anderson I've been wondering... how exactly
>do they do this filtering to change the sound of someone's voice, or
>to make it sound like 3 people singing at once...?

Well, there's two kinds of boxes.  The 'vocoder' takes a microphone
input and modulates the signal with an external source, usually a
synthesizer circuit of some kind playing one note.  The vocoder works
great for speech, not so much for singing, although there's a
brilliant passage in "Boom! There She Was" by Scritti Politti which
features Roger Troutman singing some scat vocals through a vocoder
which is being modulated by a minimoog... 

The harmonizer is a device which takes your voice and electronically
alters the frequencies in it (how, I'm not exactly sure) to produce a
harmony line with it. 

With the advent of digital sampling technology, all this stuff is now
a piece of cake, and you can buy cheap boxes to do it.  I have a
cartridge for my computer which when coupled with appropriate software
can transform the pitch of any incoming signal.  If you put a digeridu
into it playing only one note (since that's all they can play) and
then played a melody on a MIDI keyboard, it would 'play' the melody
with a digeridu sound.  I used this effect for the live version of
"Running Up That Hill" which was done at the Katemas party in July.  I
used it as basically a digital version of the Chipmunks vocal effect.
It has the advantage that you can sing in your normal voice at normal
speed and you still come out sounding like a weasel on helium, whereas
the Chipmunks stuff was all done by speeding up the tape and involved
speaking... really... slowly... so that the pacing came out right when
the tape was played back fast. 

All clear?


+---------------------- Is there any ESCAPE from NOISE? ----------------------+
|  |   |\       | jsd@gaffa.mit.edu | "I like George Bush, but this `kinder,  |
| \|on |/rukman | jsd@umass.bitnet  | gentler' crap is killing us." - D.Trump |
+-----------------------------------------------------------------------------+