Newsgroups: comp.speech
Path: pavo.csi.cam.ac.uk!warwick!pipex!uunet!hearst.acc.Virginia.EDU!murdoch!ash.cs.Virginia.EDU!kph2q
From: kph2q@ash.cs.Virginia.EDU (Kenneth Hinckley)
Subject: Re: Change playback speed without changing its pitch
Message-ID: <CKMMCw.C32@murdoch.acc.Virginia.EDU>
Sender: usenet@murdoch.acc.Virginia.EDU
Reply-To: kph2q@ash.cs.Virginia.EDU (Kenneth Hinckley)
Organization: University of Virginia
References:  <CKGz35.4A6@ariel.cs.yorku.ca>
Date: Thu, 3 Feb 1994 02:17:19 GMT
Lines: 29


There was a very good paper in the ACM UIST '93 conference (User 
Interface Software & Technology) this year that dealt with this
subject.  One interesting way to do it involved playing 
consecutive samples in opposite ears, but overlapped for half of 
the sample interval:

original samples: 
              | 1 | 2 | 3 | 4 | 5 | 6 | ...

"compressed" samples:

  Left ear:   | 1 | 3 | 5 | ...
  Right ear:    | 2 | 4 | 6 | ...

The effect is that you play back at 2x the speed, but the user 
doesn't perceive any pitch change.

Check out the paper for some of the more sophisticated 
techniques that were tried.  The author was Barry Arons, of the
MIT Media lab.

Ken

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Ken Hinckley (kph2q@virginia.edu)
University of Virginia
Neurosurgical Visualization Laboratory / Dept. of Computer Science
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