Difference thresholds for intensity perception of whole-body vertical vibration: effect of frequency and magnitude.
Difference thresholds for seated subjects exposed to whole-body vertical sinusoidal vibration have been determined at two vibration magnitudes [0.1 and 0.5 ms(-2) root mean square (r.m.s.)] and at two frequencies (5 and 20 Hz). For 12 subjects, difference thresholds were determined using the up-and-down transformed response method based on two-interval forced-choice tracking. At both frequencies, the difference thresholds increased by a factor of five when the magnitude of the vibration increased from 0.1 to 0.5 ms(-2) r.m.s. The median relative difference thresholds, Weber fractions (deltaI/I), expressed as percentages, were about 10% and did not differ significantly between the two vibration magnitudes or the two frequencies. It is concluded that for the conditions investigated the difference thresholds for whole-body vibration are approximately consistent with Weber's Law. A vibration magnitude will need to be reduced by more than about 10% for the change to be detectable by human subjects; vibration measurements will be required to detect reductions of less than 10%.
Morioka
M
M
Human Factors Research Unit, Institute of Sound and Vibration Research, University of Southampton, United Kingdom.
Griffin
M J
MJ
D000328:Adult; D000465:Algorithms; D001309:Auditory Threshold / Q000502:physiology; D004056:Differential Threshold / Q000502:physiology; D018594:Human Body; D006801:Humans; D008297:Male; D010465:Perception / Q000502:physiology*; D014732:Vibration