Localization of virtual sound at 4 Gz.
BACKGROUND
Acceleration directed along the body's z-axis (Gz) leads to misperception of the elevation of visual objects (the "elevator illusion"), most probably as a result of errors in the transformation from eye-centered to head-centered coordinates. We have investigated whether the location of sound sources is misperceived under increased Gz.


METHODS
Visually guided localization responses were made, using a remotely controlled laser pointer, to virtual auditory targets under conditions of 1 and 4 Gz induced in a human centrifuge. As these responses would be expected to be affected by the elevator illusion, we also measured the effect of Gz on the accuracy with which subjects could point to the horizon.


RESULTS
Horizon judgments were lower at 4 Gz than at 1 Gz, so sound localization responses at 4 Gz were corrected for this error in the transformation from eye-centered to head-centered coordinates. We found that the accuracy and bias of sound localization are not significantly affected by increased Gz.


CONCLUSIONS
The auditory modality is likely to provide a reliable means of conveying spatial information to operators in dynamic environments in which Gz can vary.
Sandor
Patrick M B
PM
Institut de Médecine Aérospatiale du Service de Santé des Armées, Brétigny-sur-Orge, France. pmb_sandor@imassa.fr
McAnally
Ken I
KI
Pellieux
Lionel
L
Martin
Russell L
RL
D000054:Acceleration; D000328:Adult; D000704:Analysis of Variance; D002498:Centrifugation; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D006801:Humans; D018471:Hypergravity; D008297:Male; D008875:Middle Aged; D009949:Orientation / Q000502:physiology; D013017:Sound Localization / Q000502:physiology*; D018561:Space Simulation