[sdiy] Speech synthesis chip

[jbv]

Richard,,

> >  Of course, this is mainly due to the different
> >analysis resolution, and this is the point : using VC-BPF as formants
> >gives more degrees of freedom in parameter settings than a vocoder :
> >central frequency, bandwidth & Q can be set / modified independently
> >and smoothly for each band...
>
> It also introduces a set of complex phase relationships which makes the
> whole thing far harder to control than you might think.
>
> Don't forget a BPF has a phase response as well as a frequency response.
> Whether you put BPFs in series or use them in parallel, you'll get
> 'interesting' phase effects which sound nothing like real vocal formants.
>
> I know because I tried this for my first year uni project, and it didn't
> work. :-)

Thanks for this info. However I've produced very realistic (or at least"more
than acceptable") vowel sounds with a phase vocoder, using
sound sources such as synth chords and orchestral sounds and a set of
formants.
I understand that the algos used in a phased vocoder might be different from
a set of BPFs in parallel, but OTOH the Votrax / Artic SC02 chip also
uses a set of analog BPFs in parallel and the result is quite good.
You probably know that Kraftwerk has used this chip for some of their
synthetic voices (not the basic Speak & Spell sounds in Computer World,
but some parts on Electric Cafe and The Mix) that are actually external
sound sources processed by the chip, and the result is IMHO slightly
better than a usual 8 band vocoder...

> I'd be very surprised if you get something that sounds much better than a
> good vocoder using purely analogue technology.
>
>

Nevertheless my main goal isn't to synthesize realistic singing voice,but
rather to be able to generate a vocal signal (with a quality closed to
a vocoder) without having to sing / speak the words in the first place...
I'm sure there are plenty of interersting / funny experiments to be done
with such a device...

BTW nobody answered my main question so far : what is (are) the best
design for analog BPFs to be used as formants ?

JB