[sdiy] Has anyone built a voice pitch tracker?

[Theo]

Think for (voice) pitch tracking the best option is to go digital.
After a FFT finding the pitch is a lot less difficult.

Theo


From: <harrybissell at prodigy.net>

> I've tried this electronotes circuit as well.
>
> The reason it does not work on guitar is because the (very real) stiffness
of the strings makes the harmonics sharp... the beating
> means that eventually, there will be a point where the primary and
> secondary peaks are equal.
>
> Voice is different... The harmonic content cannot be predicted
> accurately.
>
> The usual technique is to use a lowpass filter, over the two octave
> range it might work (only 24dB-48dB loss)... but it will add phase
shift...
>
> Then the harmonic "should" be less in amplitude... you hope wish pray.
>
> H^) harry
>
>
> >Dan wrote:
> >> 1. I need to eliminate the second harmonic - and when I sing very low
> >> the second harmonic is within the range of interest, so it can´t be
> >> filtered out with conventional filters.
> >Ah, the joys of pitch extraction.  I've had exactly the same issue (I
> >think) when trying to extract pitch from an electric guitar signal.
> >While I don't have a specific answer for you, in Electronotes # 53
> >Bernie Hutchins covers a technique which might be worth experimenting
with.
> >It basically involves using a peak detector type envelope follower to
> >generate a DC voltage that tracks the peaks of the original waveform.
> >The time constant of this should be adjusted so it doesn't miss too many
> >peaks (it will have lots of ripple but I think that's ok).
> >Then take this envelope (properly scaled), and use it as a reference to
> >a comparator of which the original signal is the input.  The idea is to
> >trigger the comparator on the fundamental peaks and not the second
> >harmonic peaks.  In a working situation, the output should be a pulse
> >train at fundamental frequency.
> >This technique falls apart when the second harmonic is as big as the
> >fundamental (this happened in my guitar example and pre-filtering plus
> >some other jumping through of hoops helped).
> >I'm not sure if that helps you get where you're going but I thought I'd
> >throw it out there.  I'd be happy to copy the article for you.  Let us
> >know what you come up with!
> >Buck
>
>
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