2019 Volume 12 Issue 3 Pages 153-160
The aims of this study were to examine the effect of frequency contents on discomfort of standing persons exposed to fore-aft, lateral and vertical whole-body vibration (WBV). Twelve male subjects were exposed to totally 81 stimuli that comprised three types of frequency contents with three acceleration magnitudes (0.2, 0.4, and 0.8 m/s2 r.m.s.) along fore-aft (x), lateral (y) or vertical (z) direction. The subjects with standing posture on the platform of the vibra tion test rig rated the subjective discomfort for each stimulus. The presentation order of test stimuli was randomized and each stimulus was repeated three times. The subjective scale for discomfort was calculated by using the category judgment method. In the fore-aft and lateral direction, most of the lower limits of the categories for low frequency and high frequency-weighted vibration stimuli significantly resulted in higher vibration acceleration magnitudes than those for constant power spectrum vibration stimuli. In contrast, in the vertical direction, difference of frequency contents did not significantly affect the subjective response. Also the lower limits of all the categories in the fore-aft and lateral direction were higher than those in the vertical direction. The results suggest that the effect of emphasized low or high frequency contents appears in tolerant perception of discomfort to WBV in the fore-aft and lateral direction. Standing people respond more sensitively to WBV regardless of vibration frequency contents in the vertical direction than in the fore-aft and lateral direction.
