Speech Synthesizers

[Andrew Schrock]

On Wed, 18 Nov 1998, Martin Czech wrote:
> From my experiments it is not so important where the formants exactly
> are, or what bandwidth, but the whole movement (yes, formants move
> during speech, a mechanical equivalent to a bp vcf...) is the important
> thing. The ear seams to evaluate how it moves. If there are only three
> main formants, it looks a bit strange to use a 20 channel fixed filter
> bank for a vocoder synthesis. But how can one extract formant data out
> of a given spectrum?

This is quite true... formants in many things are non-harmonic (speech,
woodwind instruments and the like) and are quite hard to synthesize IMO.
Why do you think a vocoder sounds so "robotic", even with more formants? 
Even most of the additive synthesis synths out there have trouble with
synthesizing non-harmonic formants... sometimes being nonperiodic or
even chaotic! Not the kind of thing you can stick under control of an
envelope. I mean, synths like the k5000/k500 series is a good start, but
there's much farther to go in terms of additive/formant synthesis if we
are to fully exploit it IMO. 

> It is quite illustrating to try to record backwards speech, ie. to try to
> speak in such a way that the speech sounds correct if the tape is played
> backwards. You will see that the written word is sometimes not a good
> phonetic description, eeelreeelk tiawk zith zoosh snetnezz tsaaal ethh  !

I was just doing this today with my newly acquired casio sk-8. Com'on,
like you don't want one! :) It was a birthday present besides.. when I was
a kid me and a friend used to use a casio SK to record us swearing,
reverse the sample, then try to record a new sample such that when it was
reversed it sounded like the original swear. I think this took up more of
our time than playing nintendo, but I can't be sure. Hey, where'd my youth
go again??? 

What other semi off-topic stories can I tell about this... the scenes in
twin peaks shot in the black lodge (red curtain, only visited in dreams or
by doomed characters such as laura palmer) were all shot backwards. 
Apparently the guy playing the dwarf (aka 'the arm') figured out how to
walk/talk backwards previously in his career and proceeded to teach the
rest of the cast... this is why the scenes look so disconcerting,
especially when he starts to "dance". 

formants, dwarves, casios... must be time to sleep. 
Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|