title: Localization of virtual sound at 4 Gz.
abstract: 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.
authors.affiliation: Institut de Médecine Aérospatiale du Service de Santé des Armées, Brétigny-sur-Orge, France. pmb_sandor@imassa.fr
authors.forename: Patrick M B
authors.initials: PM
authors.lastname: Sandor
authors.forename: Ken I
authors.initials: KI
authors.lastname: McAnally
authors.forename: Lionel
authors.initials: L
authors.lastname: Pellieux
authors.forename: Russell L
authors.initials: RL
authors.lastname: Martin
mesh_terms: 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