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From: dandb+@cs.cmu.edu (Dean Rubine)
Newsgroups: comp.dsp
Subject: Re: Autocorrelation Pitch Tracker
Message-ID: <1991Apr7.040723.1252@cs.cmu.edu>
Date: 7 Apr 91 04:07:23 GMT
References: <78395@bu.edu.bu.edu> <1991Apr6.062906.11886@cs.cmu.edu> <51258@apple.Apple.COM>
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In article <51258@apple.Apple.COM> malcolm@Apple.COM (Malcolm Slaney) writes:
>Everybody here has really been talking about periodicity detectors and NOT
>pitch detection.

    Come, now.  I think most of us realize that pitch is a perceptual
quantity, or would if we thought or read about it a bit.  That doesn't
lessen the desire to solve a practical problem: determine the instantaneous
fundamental frequency at successive points in a quasi-periodic signal.  Of
course even this problem statement is too vague, but it's probably good
enough, because it's usually considered as a means to some end.  For example,
the original poster might be building a real-time transcription system for
vocalists.  Or a system that listens to a trumpet and synthesizes an
accompaniment.  Or a better pitch-to-MIDI converter. Note I've used the
term "pitch" here, even though I am not overly concerned about perception.
I'm just going along with the rest of the world, as was the original poster.
Face it, these things are called "pitch detectors" even though the use of the
term "pitch" may be technically incorrect.  While pitch detectors may be
judged on how often they report the same pitch as a skilled human would,
in most applications the hard cases, where perception is ambiguous, can be
ignored. 

   As for his short signal not having a perceptable pitch, that may be true
but that still doesn't help him to solve his problem.  He knows what he means
by pitch, as do the rest of us, even Maclcom Slaney I suspect. 

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