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From: randys@mipon3.intel.com (Randy Steck)
Newsgroups: sci.electronics
Subject: Re: Comb filters
Message-ID: <883@omepd>
Date: Wed, 15-Jul-87 15:07:49 EDT
Article-I.D.: omepd.883
Posted: Wed Jul 15 15:07:49 1987
Date-Received: Sat, 18-Jul-87 06:35:53 EDT
References: <8707110358.AA14182@unisoft.UNISOFT> <7150@shemp.UCLA.EDU> <19698@ucbvax.BERKELEY.EDU>
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Reply-To: randys@mipon3.UUCP (Randy Steck)
Organization: Intel Corp., Hillsboro
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In article <19698@ucbvax.BERKELEY.EDU> kavaler@zion (Robert Kavaler) writes:
>
>
>The human ear is sensative to the relative phase difference between sounds
>entering both ears.  This is how we (and animals) can tell where sounds
>originate.  By shifting the phase difference a sound can "appear" to 
>come from elsewhere.  Phase-shifting techniques are used extensively in
>all sorts of stereo equipment, from cheap Boom-boxes to very expensive
>mixers.

I've sometimes wondered about this......

It seems to me that the phase of the signal does not have as much to do
with apparent direction as the delay and intensity of the sound reaching
the ears does.  Given the wavelength of the sound, phase-shifting would
seem to have a similar effect as changing this delay.  A quick calculation
shows that the delay apparent (worst case) from one ear to the other is
about .2 usec.  Is this sufficient to resolve directions?  

Also, it is well-known that the eye requires an inherent "jitter" to
resolve images and avoid saturating the optical receptors.  Do the ears
also require some "jitter" to resolve the direction from which a sound
originates?

  Randy Steck
  Intel Corp.