Hearing and performance during a 70-h exposure to noise simulating the space station environment.
BACKGROUND
Elevated hearing thresholds have been documented in some astronauts after long-term spaceflights although noise levels were lower than those normally associated with noise-induced hearing loss in ground-based operations. The present study was conducted to determine whether prolonged exposure (70 h) to levels (72 dBA) recorded on the International Space Station (ISS) service module would impact diverse measures of auditory function, as well as cognition and memory, motivation, and cardiovascular function.


METHODS
Five mixed gender subgroups of five normal-hearing subjects, aged 20-50 yr, were sequestered for 70 h in an environment that modeled conditions on the ISS. They were assigned to one of three background conditions: quiet (n = 5), continuous noise from the ISS service module (n = 10), or continuous noise during the day only (n = 10). Subjects were tested repeatedly within and across days as individuals or pair mates.


RESULTS
There were no negative effects of the noise on any of the outcome measures. Introduction of a delay or noise in a communication channel used in the assessment of speech communicability significantly affected the time taken for joint problem solving by partners.


CONCLUSIONS
The results of this study were not consistent with the observation of hearing loss measured after spaceflights. Nor were changes evident in cognition, motivation, or cardiovascular function. Factors which might account for the discrepancy are discussed.
Defence Research and Development Canada-Toronto, Human Factors Research and Engineering Section, DRDC Toronto, P.O. Box 2000, 1133 Sheppard Ave. West, Toronto, Ont., Canada M3M 3B9. Sharon.abel@drdc-rddc.gc.ca
Sharon M
SM
Abel
Brian
B
Crabtree
Joseph V
JV
Baranski
David G
DG
Smith
Megan M
MM
Thompson
Herman J M
HJ
Steeneken
Jan A
JA
Verhave
Jay C
JC
Buckey
Donna L
DL
Alvarenga
Jean-Marc
JM
Comtois
D000328:Adult; D001273:Atmosphere Exposure Chambers; D001309:Auditory Threshold / Q000502:physiology*; D005260:Female; D006309:Hearing / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009622:Noise; D011571:Psychoacoustics; D011597:Psychomotor Performance / Q000502:physiology*; D013026:Space Flight; D018561:Space Simulation; D011795:Surveys and Questionnaires; D013997:Time Factors