Hi Robin,
Thanks for the references: the minimum audible angle (MMA) concept is inter=
esting.
With any on location localization test, even when the exact position of a s=
ound source is known, reverberations with the physical surroundings will al=
ways distort the source's image to some degree. For a typical walk around =
test, I think clock position at increments of hour (30 degrees)or half-hour=
(15 degrees) gives sufficient information to describe the general localiza=
tion characteristics - for an array, on a specific location, for a specifi=
c playback environment, and subjective to the spacial resolving abilities o=
f the listener.
Beyond clock positions or angular degrees on the horizontal plane, vertical=
, and radial distance modifiers may be useful. For most listeners and typic=
al playback systems, vertical modifiers "high" and "low" might be enough. F=
or radial distance, "near, mid, and far" always seam a bit inadequate to me=
.
John Hartog
rocscallop.org
--- In "robin_parmar_sound"
> I believe instead it is more appropriate to follow Mills' vocabulary of t=
he minimum audible angle (MAA), which refers to the smallest detectable amo=
unt of sound source displacement. Like other JNDs (just noticeable differen=
ces) it depends on the frequency of the source. Remarkably, this can be as =
precise as 1 degree (at 500 Hz), but of course this was in a tightly contro=
lled listening environment.
>
> Using MAA to measure the quality of a location recording is a different m=
atter -- but is an intriguing possibility! Certainly a listener would be ab=
le to distinguish a lot more than 3 or even 9 distinct sound source positio=
ns... likely more than 20. This makes sense when one considers that we hear=
a moving source in the stereo field tracing a smooth path, and not jumping=
from one discrete position to another.
>
> Refs:
> Kapralos, B., Jenkin, M., and Milios, E. (2006) "Sonel mapping: A stochas=
tic acoustical modeling system". Proceedings of the IEEE International Conf=
erence on Acoustics, Speech and Signal Processing.
>
> Mills, A. W. (1958) "On the minimum audible angle". Journal of the Acoust=
ical Society of America 30.4, 237=96246.
>
> -- Robin Parmar
>
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