Re: Room acoustics requirements for a localization experiment

[Al Bregman <al.bregman@xxxxxxxxx>]

Hi Daniel,

The obvious answer, "as little reverberation and echo as possible" may
not be the right answer.  It is quite possible that the harm to
localization that is created by a hearing disorder will increase as
the room becomes more reverberant, and that by testing in an anechoic
environment, one may miss a substantial amount of this deficit.

It might be useful, therefore, to test in two different environments,
a room with normally reflective surfaces, and the same room with
deadening material on these surfaces, and compare the results.

Also the choice of a signal source is relevant.  How directional is
the signal that is coming out of the speaker?  Again, this could
influence the results.  The difference between impaired and normal
listeners might be greatest in a reverberant room, with an
omnidirectional emission of sound.

So what is the purpose of the experiment, a reference value in a
sound-deadened room, or applicability to the world outside the lab?
This should determine the choice of conditions.

Cheers,
Al
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Albert S. Bregman, Emeritus Professor
Psychology Department, McGill University
1205 Doctor Penfield Avenue
Montreal, QC, Canada H3A 1B1.
Office:  Phone: (514) 398-6103, Fax: (514) 398-4896
http://webpages.mcgill.ca/staff/Group2/abregm1/web/
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On Fri, Apr 29, 2011 at 10:17 AM, Daniel Oberfeld <oberfeld@xxxxxxxxxxxx> wrote:
> Dear list,
>
> a colleague from the medical department asked me for help. He wants to
> measure the minimum audible angle (MAA) in patients with hearing problems,
> in order to detect deficits in localization compared to normally hearing
> listeners. In his medical/audiology setting, no anechoic room is available.
> He wants to use broadband stimuli, approximately 100 Hz to 8000 Hz. Now he
> is wondering what the minimum requirements concerning room acoustics for
> such an experiment are.
>
> As I know that many experts in the field of localization are subscribed to
> this list, I'd be very interested in your opinion!
>
> I'd guess that an attenuation of the direct reflections is most important?
>
> And probably someone might also be able to recommend some simple technical
> measures one could take for making a normal, non-anechoic audiology room
> more suitable for such an experiment. The room size is approximately 3 x 4 x
> 2.5 meters.
>
> Looking forward to your responses!
>
> Best
>
> Daniel
>
> --
> Dr. Daniel Oberfeld-Twistel
> Johannes Gutenberg - Universitaet Mainz
> Department of Psychology
> Experimental Psychology
> Wallstrasse 3
> 55122 Mainz
> Germany
>
> Phone ++49 (0) 6131 39 39274
> Fax  ++49 (0) 6131 39 39268
> http://www.staff.uni-mainz.de/oberfeld/
>



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