Pitch detection in voice (singing)

Rune Allnor wrote:

   ...

> and for a continuous, periodic, non-constant phase function v_g(w),
> the group delay must necessarily become negative in some frequency
> range. So I ended up with non-causal signals where I didn't want any.

Negative group delay isn't necessarily non causal. Anomalous dispersion 
is a likely cause.

   ...

Jerry
-- 
Engineering is the art of making what you want from things you can get.
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