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perception of direction of sounds

Robert Tapper rjt at siva.bris.ac.uk
Fri Sep 1 03:37:29 EST 1995

bjparker at aol.com (BJPARKER) wrote:
>What you need is a psychoacoustician... psychacoustics or the perception
>of sound is a wonderful area of study. Also, you are correct that there is
>a large volumn of information on this topic.  Can you narrow your question
>down a bit?
Well I'm really only interested in the underlying acoustic information..
that the brain makes use of, not in the way it processes it. Replies..
from others and also replies to a similar question I posted in..
alt.sci.physics.acoustics have given me a great deal of information..
which I could crudely summarise, at the level of detail I require, as:
"both intensity differences and phase differences are used, the..
former for high frequency sounds, the latter for low frequencies"
This is clearly enough to distinguish left from right, but I remain..
puzzled by the apparent ability of the brain to determine the location..
of a sound source located on the mirror-symmetry plane of the head..
( I expect you people have some other name for this ). Because of..
the symmetry the two ears will detect precisely the same signal..
even if the shape of the pinnae and other factors alter the perceived..
spectrum of the sound. If you have no a priori information about..
the loudness or frequency content of a sound there seems to be no..
physical information available on which the brain can base a..
perception of the position of a sound source in this plane.
In fact a reply in alt.sci.physics.acoustics from someone involved..
with experiments in this area indicated that this perception was only..
possible with a wide-band signal, was affected by changing the shape..
of the subjects pinnae and that errors were fairly common.

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