Newsgroups: comp.speech
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From: rolfe@fraser.sfu.ca (Christopher John Rolfe)
Subject: Re: Pitch Control
Message-ID: <rolfe.719356862@sfu.ca>
Sender: news@sfu.ca
Organization: Simon Fraser University, Burnaby, B.C., Canada
References: <1992Oct16.191849.28538@ee.ubc.ca> <1992Oct17.065722.12698@wixer.cactus.org>
Date: Sat, 17 Oct 1992 21:21:02 GMT
Lines: 29

sparky@wixer.cactus.org (Timothy Sheridan) writes:

>In article <1992Oct16.191849.28538@ee.ubc.ca> vtrinh@ee.ubc.ca writes:
>>
>>I have a PCM waveform (vowel sound), and I would like to
>>alter the pitch of the sound.  Does anybody have any
>>ideas on how to do this?
>>

>what if you slowed or speeded it up a bit?

	You could adjust the playback sample rate, but
only 5 or 10 % either way ( about a semitone );  any more and
the resultant shift in formants causes chipmunk, or slowed tape effects.

	What you're looking for is some kind of time-invariant pitch
shifting, which maintains the formant structure of the original vowel.
Try a vocoder, combined with a 1/3 octave equalizer.  If you can't
access a vocoder, several sampling programs offer time-invariant pitch
shifting ( Sound Tools by Digidesign, Steinberg Avalon ) if you can
get to one of them.  You'd still need to filter the result.



-- 
Chris                   | 2617 East 4th,| If brevity is the soul of 
rolfe@sfu.ca            | Van., B.C.    | wit, what is semibrevity
Simon Fraser University | V5M 1K5       | the soul of?
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