[sdiy] Formant filters, yay!

[Richie Burnett]

> Incidentally, whether you sync the windowed waveform or not is one of the 
> differences between the several flavours of this type of thing. Some 
> places say you should, other places seem not to bother.

If the sinewaves don't need to be sync'd, then you could probably get away 
with using something like the magic circle algorithm to generate your sines 
very efficiently in only a few CPU cycles.

> It sounded vocal, ish, but I wasn't that impressed. It made a series of 
> AEIOU-type sounds when you twiddled it, but seemed like a lot of work for 
> that result. I've had pretty similar sounds out of a couple of resonant 
> filters.

That's what I was wondering.  IIR biquads are quite cheap to implement on 
modern DSPs and give you complete freedom in your choice of formant 
position, formant width and intensity.

-Richie,