Getting Vocal in my old age....

[jbv]

patchell :

>     This is the nasty part.  I want to have a control voltage that will
> "tune" each vowel.  So, 0 volts will be "ee", 1 volt will be "i", etc...  If
> you look at the table of Formant frequencies here:
>
> http://www.silcom.com/~patchell/voicesynth/voicesynth.html
>
>     You can get an idea of what I mean.  I think it would be kind of neat to
> be able to have the filter morph from one vowel to the next (I could be
> wrong, but, my Nord Modular has a filter that does something like this, and
> it does sound kind of neat).  I was tempted at one point to use a micro with
> an A/D to do the mapping, but that would be "too digital". (I may, in the
> end, do that anyway, but I wanted to try an analog solution first.  The
> micro idea is apealing because you could remap the vowels in any order you
> wanted).
>
>


Mmmmh... Most tables of formant frequencies I've seen
included central frequency as well as bandwith and relative
amplitude for each formant... I doubt that giving each formant
the same bw & Q wil produce acceptable "vocal" sounds...

Another parameter to consider is the spectral content of the
excitation source (just like in a vocoder).

Actually, 18 months ago I spent some time brainstorming
on a similar project of a VC filter bank based around the
VCF CEM chip (forgot ref #), and did some DSP simulation,
and things appeared much more complex than I first thought...

As for morphing between vowels, I've always wondered
if the transition between 2 vocal sounds was a simple
interpolation between formants parameters (F, bw & Q),
or if it was some more complex crossfades between
spectral contents...

At least a bank of formant filters could allow to make
choirs from lush synth chords (or from orchestral sounds).
But regarding speech simulation, some more complex technics
are involved, especially regarding transitions between sounds...
AFAIR, some speech synth systems in the early 80's were
using transient between vocal sounds, instead of formant
tables...

jbv