Effect of normobaric hypoxia on sound localization.
BACKGROUND
Three-dimensional (3D) audio displays have considerable potential for conveying spatial information in the aviation environment. How reliably these displays will function in that environment will depend in part on the extent to which sound localization is affected by hypoxia. Many aircraft systems operators are routinely exposed to mild hypoxia, and all are at risk of exposure to more severe hypoxia.


METHODS
We have examined hypoxia's effect on localization by measuring the localization performance of four subjects exposed to simulated altitudes of 0, 1200, 2400 and 3700 m above sea level for about 30 min. Sounds to be localized were presented from a free-field source at locations covering 360 degrees of azimuth and extending from -47.6 to + 80 degrees elevation.


RESULTS
Localization performance was statistically indistinguishable across the altitudes tested. Average localization errors ranged from 12.6 degrees +/- 0.7 SE at 2400 m to 14 degrees +/- 0.84 SE at 0 m.


CONCLUSIONS
The finding that hypoxia induced by exposure to simulated altitudes as high as 3700 m has no effect of sound localization is encouraging with respect to the continued development of 3D audio displays for use in the aviation environment.
Martin
R L
RL
Aeronautical and Maritime Research Laboratory, Defence Science and Technology Organisation, Fishermens Bend, Victoria, Australia. Russell.Martin@dsto.defence.gov.au
Watson
D B
DB
Smith
S E
SE
McAnally
K I
KI
Emonson
D L
DL
D000328:Adult; D000337:Aerospace Medicine; D000531:Altitude; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000097:blood / Q000503:physiopathology*; D008297:Male; D013017:Sound Localization