external ears' influence on hearing

K.R.Catchpole3 at student.lut.ac.uk K.R.Catchpole3 at student.lut.ac.uk
Mon Mar 20 04:52:22 EST 1995

In article <3jonse$4si at geraldo.cc.utexas.edu> sirianni at uts.cc.utexas.edu (Jeffrey Sirianni) writes:
>In article <3jnlcb$4ua at calvin.usc.edu>, phelps at calvin.usc.edu (Charles V. Phelps) says:

<Lots of stuff about hearing in noise deleted>

The ability to hear speech in a masking noise (the so called 'cocktail party
effect') is dependent upon a number of factors including auditory localisation
(the ability to tell the direction and distance of a sound source).  Basically,
if you can tell from where the sound originates in space, you've got a much
better chance of hearing the message it carries (this may make between 3dB and
6dB difference).  The pinna is highly influential in localisation, as are head
movements and a great number of other factors.

>Audiometric testing has been "standardized" so that pinna shape does
>not effect the results of the test.  I know that this is not "real world"
>data, but we use it as a standard across all people.

Recent studies (Wightman, 1987 etc. - if you need a list I can look them up)
have shown that if you give subjects a free field to eardrum transfer function
that is not their own, then their ability to hear masked speech will be
reduced.  The important thing is that the further each subjects transfer
function is away from the simulated one, the worse the affect will be.  Each
subject is different.
Therefore there is NO standardised pinna shape which will affect people in the
same way.

>If you are interested in pinna effects, there is a classic 1972 (?) article
>by Shaw, where each of the outer ear componets were analyzed in their relative
>contribution to hearing and localizing.  If someone knows the reference off-hand,
>I'm sure it would be appreciated.

Really ??  If you've got the reference I'd be interested.  After all, with
each pinna different, there must be one hell of a lot of components just for
that alone.

>>Charles Phelps
>>phelps at calvin.usc.edu
>Jeff Sirianni     @(((<{
>sirianni at uts.cc.utexas.edu
>jgsaudio at aol.com

			#########	You may know what I don't know
>> Ken Catchpole <<	###   ###	But not that I don't know it.
			###   ###	So you will have to tell me everything..
							'Knots' - R D Laing

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