Human Performance as a Function of Direction and Frequency of Whole-Body Vibration.
Final rept. Sep 68-Sep 69,
AEROSPACE MEDICAL RESEARCH LAB WRIGHT-PATTERSON AFB OHIO
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Human performance on a task complex made up of two-dimensional compensatory tracking and visual discrimination reaction time was measured during sinusoidal vibration in each of the three major translational axes X, Y, and Z. A separate experiment was conducted for each axis, with the subjects seated upright in all experiments. Frequencies tested in each axis were 1, 3, 5, 8, and 11 Hz, at 0.2g and 0.4g. Duration of vibration at each frequency was 9 minutes. Y-axis vibration produced pronounced decrements in both tracking and reaction time with the greatest interference occurring at 3 Hz and 1 Hz, and the least at 11 Hz. For the X and Z axes low-frequency effects were smaller and performance curves across frequency, for constant g levels, were flatter with slightly greater effects at 5 Hz. Horizontal and vertical component scores for the tracking tasks were analyzed with regard to mechanical interference effects for each direction of vibration, and an analysis of frequency effects was made in relation to body resonance phenomena. Author
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