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Re: auditory localization

You haven't said whether you will be encoding the required inter-aural
differences to the loud speakers in such a way that you would only place
'images' in the speakers, or conversely using speaker pairs (or other
configuration) to make inter-speaker imagery. If it were the second case,
then  cross talk and room acoustic would confound the intended interaural
differences and the method of generating the 'phantom image' has a
significant impact on results; indeed, speakers used behind the 90-degree
axis can aid localisation and 'focus' of images in the frontal plane.
If you are restricting images to actual speaker locations (so that a given
signal is only ever fed to one speaker at a time), then you'd need quite a
lot of speakers to cater for the notional acuity of 1-2 degrees aroud the 0
degree azimuth, elevation point. Also, if the room isn't anechoic, then the
directivity pattern-with-frequency is a problem for IIDs and ITDs, and
speakers can be spectacularly poor localisation 'targets' when compared to
many 'real' sources.
This is without taking into account interactions with visual
stimulus-characteristics, which I see someone else has pointed out.
good luck,
----- Original Message -----
From: "Elyana Makowski" <elyana_makowski@hotmail.com>
Sent: 07 May 2004 14:30
Subject: auditory localization

> Hi,
> I am a PhD student and my research project is on the use of localization
> cues (ILD and ITD) in the  horizontal plane.  My set up consists of 11
> speakers arranged at 18 degree intervals from -90 to +90 degrees in the
> azimuthal plane.  Currently, I have tested normally hearing subjects, and
> will soon be testing hearing aid users and cochlear implant users.
> Recently, an issue has been brought up as to the number of speakers that I
> am using, with the suggestion being made that better results could be
> measured if I used more speakers.  My question is does anyone know how
> speakers are necessary to accurately measure the average localization
>   How many speakers are enough?
> Thank you,
> Elyana
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