Pitch calculation (FFT or autocorrelation)

robert bristow-johnson wrote:
> anyway, any application i can think of for a PDA desires the pitch
> returned to be the same as the perceived pitch.  if the note sounds
> like middle C, the PDA should say it's middle C, not the C an octave
> below nor the F that is 7 semitones lower than that.

Robert, I agree.

> the problem
> is that with many instruments and the human voice, both spoken and
> singing, sometimes the nature of the vibration of whatever it is (reed,
> lips, strings, vocal cords, or a column of air) is that one vibration
> is nearly identical to the next but slightly different but the
> following vibration is very much like the first.  every odd cycle is
> more identical to each other than they are to the even cycles.

Moreover in some signals the odd and even pulses are different
significantly and then one can hear a pitch somewhere between
F0 and F1. The good examples are here:

http://www.mrc-cbu.cam.ac.uk/cnbh/web2005
/teaching/sounds_movies/Pitchchroma&height.htm

My interest is to research why and how does the human's pitch
perception mechanism work this way.
A problem of waveform repetition period becomes difficult when
two subsequent pulses are similar but not identical. The result
of two pulses (or parts of signal) comparison depends on the
definition (or concept) of similarity. Dmitry Terez has his own
concept and his own method. Just one of others. I don't see a
breakthrough. Nothing to argue about. The only thing that could
be interested for someone (not for me) is how much the concept
of Dmitry differs from the auto-correlation or from AMDF.
I can say only that the human's pitch perception mechanism
differs from these waveform comparison methods. The spectral
analysis also doesn't work well.

Sorry for my probably poor English.
Vladimir.